It’s possible. If these are close friends who are familiar with the way you think, they might be onto something. Online tests are notoriously unreliable, especially if you’re taking the kind that accumulates by letter rather than by function.
Let’s say the test is the kind that accumulates by letter. There are some questions geared towards I vs E, some geared towards S vs N, some towards T vs F, some towards J vs P.
It’s especially easy for people to have an even split on J vs P, because the questions are usually something like, ‘Do you keep your appointments?’ To which nearly everyone responds, ‘Of course I keep my appointments! I’m a responsible person.’ Or, ‘Do you tend to work better with a deadline?’ Most of us who have gone through the schooling system have only worked with a deadline in front of us. This pushes you onto the J side. But J vs P is about being more comfortable in a position of settled decisions vs being more comfortable in a position of potential.
I can see the introvert vs extrovert being due to the ‘introvert’ culture online, and the belief that introversion is the same as introspection. I’m not as sure, though.
As for the differences between INFJ and ENFP, they have all the opposite functions. Very briefly:
Ni vs Ne
Ni: There’s more or less one way to do this. Stop getting side-tracked. Stick to the goal. I have a vision that I’m going to make happen. I’m interested in a few things and I can never get enough of them. I don’t feel the need to explore everything.
Ne: There’s a million ways to do this. Stop being narrow-minded. Consider the possibilities. I have all these potential methods that we can try in case the first doesn’t work. I’m curious about everything, but am more or less satisfied when I think I’ve learned enough about it.
Fe vs Fi
Fe: I feel for you, even if we have nothing in common. When someone smiles at me, I smile back without thinking. All humans are the same, deep down. I’m uncomfortable with bringing up a contrary opinion that I know will cause arguments. There’s a universal code for how to be a good person.
Fi: I feel for you because I understand your suffering. My feelings aren’t affected by others’ behavior. All humans are individual; I am different and unique. I’m uncomfortable with staying silent if I’m not being true to my own conscience. There’s a different way for each person to be good.
Ti vs Te
Ti: I want to understand the problem. The world can help me learn new things about myself. I don’t care about efficiency; I’m interested in accuracy. I’m slow, meticulous, and perfectionistic. I want to be true to what I know. I act in a way that makes sense to me.
Te: I want to solve the problem. I can use what I know to change the world around me. I don’t care about irrelevancies; I’m interested in efficiency. I’m practical, methodical, and sensible. I want to be effective. I act in a way that makes sense in the situation.
Se vs Si
Se: I’m highly aware of what’s going on in the moment. I find it easy to observe what’s in front of me. I like things that stimulate my senses. Note that an Ni-dom has Se as their inferior, so they will be bad at all of the above things. They are easily overloaded with sensory information and won’t be in touch with the evidence of their foreknowledge (’I don’t know how I know—I just know!’).
Si: I have an acute memory of details from the past. I find it easy to recall dates, what people wore, what they ate, etc. and I can easily tell a story without getting lost or sidetracked. I like things that remind me of my childhood. Note that an Ne-dom has Si as their inferior, so they will be bad at all of the above things. They are forgetful, scattered, and out of touch with their past. They also tend to be more impulsive.
These function descriptions apply to most type comparisons.