Myers-Briggs has become a popular way to categorize people, to generalize and maybe even understand them. Thanks to an overabundance of internet tests and opinionated bloggers, there’s a lot of information floating around out there, much of it misleading or inaccurate. As an imperfect (and often discredited) form of psychology, it’s nearly impossible to have perfectly accurate information on the sixteen Myers-Briggs types, but that doesn’t stop people from trying to figure out their own type, plus the types of all their friends, coworkers, and favorite fictional characters.

This can be a little difficult sometimes, because there’s a lot of overlap in the types, and no two people are going to fill a type exactly the same way. That being said, there are still some distinct differences that can be helpful in determining a person’s strengths, weaknesses, future actions, etc. It won’t tell you what kind of person they are, but it might give you insight into why they’re acting the way they are. If you don’t fully understand the framework, though, it’s easy to confuse similar types and then mistype people. INTJ and INTP are two types that are frequently confused—which is why you’re here. But first, let’s get a few misconceptions out of the way.

You cannot be both INTJ and INTP.
Contrary to popular internet tests, the difference between these two types is not just whether you’re more apt to judge or perceive. The two types have vastly different cognitive function stacks, meaning they have different ways of viewing and processing the world around them. They take in information differently, they reach conclusions differently. You cannot switch back and forth between the two. It’s just not how the system works. Personality types are, generally speaking, static, and receiving different results on online tests is most likely due to imprecise metrics, not your personality type changing.

INTPs are not inferior INTJs.
There’s a commonly believed fallacy that INTPs are basically INTJs, but worse. This is, of course, not true, and no one personality type is better than another. Some types might have more qualities that you admire, but that doesn’t make it a universally better type. Every type has its own strengths and weaknesses.

Myers-Briggs is not an exact science.
It’s not even really science at all. There’s some merit to it, of course, but it’s largely a pop psychology trend that gives people a way to understand themselves and the people around them. Most free internet type tests are dependent on mood and circumstance, frequently giving imprecise results, and much of the information that’s out there is incorrect and based on some blogger’s imperfect understanding of the research. As with anything, be careful what you believe.

A person is more than their type.
Asking if an INTJ and INTP can date or be friends or work together is about as illogical as asking if a Scorpio and an Aries are compatible. There might be a little bit of merit to it, but mostly it depends on the person and their temperament and values and a whole host of other things that a personality test can’t tell you. From a practical sense, MBTI is best for determining strengths and weaknesses, but even then, everyone has different struggles and different triumphs. A personality type may give you some initial insight into a person, but eventually and inevitably it becomes an untrue generalization.

If you’re trying to decide if you or someone you know is an INTJ or an INTP, there are a few easy differences to spot. But before getting into those, it’s essential to know the underlying theory that differentiates the types.

While INTPs and INTJs have a lot in common, the way they think is totally different. To explain cognitive function stacks simply, your dominant function is the strongest and most natural, while your auxiliary function feeds and supports the dominant. Those two make up the majority of how you interact with the world. The tertiary function is underdeveloped and can cause conflict, both internal and external. The final, or inferior, function is largely unconscious and can both overwhelm when it’s forced upon a person and manifest under stress in negative ways.

INTJ Function Stack: Ni-Te-Fi-Se

INTJs are governed by introverted intuition and extraverted thinking. Ni is a subconscious sorting and organizing of information, constantly working to form Te’s objective and systematic judgments into something useful. Introverted feeling and extraverted sensing form an INTJs weaker functions. Fi focuses on inner feelings, emotions, and values, and is often ignored in favor of Te’s unerring rationality. When Fi is used, the result is often an immature emotional response or a confused lack of empathy. Se concerns itself with the five senses, with concrete events happening now. As the inferior function, it causes sensory overload in over-stimulating situations, and it manifests under stress in purposeful overstimulation and often substance abuse.

INTP Function Stack: Ti-Ne-Si-Fe

INTPs are governed by introverted thinking and extraverted intuition. Ti is focused on the qualitative essence of things, holistically cataloging Ne’s information and patterns for any possible use. Introverted sensing and extraverted feeling form an INTPs weaker functions. Si recalls past experiences and focuses on the most basic sense of being, often resulting in excessive and immature nostalgia or self-focus. Fe desires harmony and affirmation and can cause discomfort in unfamiliar or high-tension social situations. Under stress, Fe manifests as uncontrollable and often disconcerting emotion.

But what does this all mean, practically?

Both INTJs and INTPs are intelligent and frequently arrogant, and they both tend to think they’re always right. They even tend to share the same dark sense of humor. These qualities are the root of most mistyping, with INTPs defaulting to INTJ because the tertiary function of Fi (I don’t like emotions!) is much more clearly understood than Si. But since both types have feeling as a weaker function, not liking emotions is not unique to INTJs. INTJs don’t like emotions because they don’t understand them and don’t find them useful. INTPs don’t like emotions because they can’t control them and find them uncomfortable. In reality, those differences are hard to discern. So here are some good ways to tell the difference between an INTJ and an INTP:

INTJs are External, INTPs are Internal

Both INTJs and INTPs have introverted functions as their dominant functions. However, INTJ’s dominant function (Ni) is a perceiving function, while INTP’s (Ti) is a judging function. Judging functions (thinking and feeling) are the functions that allow you to make, you guessed it, judgments about the world around you, and are thus the functions that can be seen more easily by other people. Because of this, INTPs tend to come off as lost in their own heads, using their auxiliary extraverted perceiving function (Ne) simply to gather all the ideas, all the patterns, all the possibilities. INTJ’s auxiliary function (Te), on the other hand, is their defining characteristic to other people, making them come off as judgmental, opinionated, and likely to beat you in an argument or die trying.

With their weaker functions, too, INTPs are immaturely focused on the inner self (Si), causing them to think constantly about where they’re at in life and how the now compares to the past—a largely internal process—and will keep themselves out of the way in order to maintain harmony (Fe). In contrast, INTJs hide and ignore their feelings (Fi), but will chase sensory experiences indeterminately because they “feel like it” (Se).

The combination of these dominant and inferior functions causes INTJs to come off as more engaged with the world—starting arguments, leading meetings when no one else seems to be able to, attending music festivals or seeking adrenaline rushes—and INTPs to come off as withdrawn—avoiding confrontation, thinking for too long before speaking or acting, seeking knowledge for knowledge’s sake.

INTJs Believe in a Right Way to Do Things, INTPs Believe in Objective Truth

For INTJs, Te gathers information, and Ni sorts it into useful categories. Think Sherlock sorting through his mind palace. INTJs know that information is simply information and that the truth looks different to different people (Te), and they know that truth can be sorted into any arrangement to make an argument (Ni). Since there are so many ways to organize facts into truths, and since INTJs are logical and practical above all else (Te), they believe that there is one Right Way to do things, usually the way they’ve figured out. This isn’t just arrogance, either—INTJs pride themselves on finding the most efficient and effective way to do anything: the Right Way.

For INTPs, Ne gathers patterns and perceptions, and Ti tries to get to the heart of them while forming an incontestable internal logic. Think Bruce Banner in the lab, thinking, processing, questioning. INTPs know that the facts are the facts (Ti), and it doesn’t matter how someone reaches a conclusion, because we should all end up the same place they did. Again, it’s not solely arrogance—INTPs have usually thought through every possibility and logically come to an indisputable conclusion.

INTJs are Forward-Thinking, INTPs are Backward-Thinking

INTJ’s Ni is focused on finding the best way to use the information that Te gathers. Potentially useful information is stored for future use, and irrelevant information is quickly forgotten, sometimes to the INTJ’s detriment. This focus on the useful leads INTJs to always be forming and reforming plans for how to make things more efficient, more functional, just all around better. Their heads are always in the future: plotting, scheming, imagining, fixing.

INTP’s tertiary Si is focused on past experiences while Ti is constantly looking for the why’s and how’s of everything that happened in the past to better inform the now. This cycle can often trap an INTP, causing them to constantly compare the past with their current situation. Even when an INTP isn’t trapped in nostalgia, Ne’s influx of information results in too many possibilities for Ti to accurately and quickly form plans. INTPs will always think through and theorize first, often resulting in a more comprehensive and easily achievable (if slower) plan than an INTJ would come up with.

INTJs are Confrontational, INTPs are Amiable

INTJ’s belief in the Right Way and general Te tendencies make INTJs more than willing to share their thoughts and opinions, because they’ve spent the time to make sure those thoughts and opinions are as correct as they can be. While still introverts, and therefore unlikely to go around picking fights, INTJs stand firm in their beliefs and won’t back down if they feel someone is questioning them or acting in an illogical or incompetent manner. These qualities tend to make INTJs come off as confrontational or contrary, whether the INTJ means to be or is just trying to make something more efficient.

INTP’s inferior Fe has them seeking social harmony to avoid uncomfortable situations, which tends to manifest itself in being agreeable, even when they don’t agree. Ti, too, in contrast with INTJ’s Te, is focused inward, so rather than expressing ideas, INTPs prefer to mull them over. INTPs try not to engage in arguments or debates, because they’re always re-evaluating how new information fits into their internal logic and forming new theories which in turn need more information. Combined with an introverted nature, these traits make INTPs more likely to come off as amiable and pleasant.

While these are by no means the only differences between INTJs and INTPs, and all INTJs and INTPs will act slightly different depending on their upbringing, values, current situation, etc. etc., these are a few surefire ways to make the final determination between an INTJ and an INTP. If, after reading this, you’re still not sure, that’s okay. It’s not a perfect science anyway. Maybe try Enneagram types, or even a Which My Little Pony Are You? test. There are a lot of ways to categorize yourself and others, but in the end we’re all just people. Don’t take yourself too seriously.