There seem to be a lot of misconceptions about the MBTI. There are four letters in every personality type. For example, I’m an INFJ. Many people will assume that and INFJ is almost the same as an INFP because they share three letters. People typically assume that J’s are organized and punctual while P’s are messy procrastinators. However, they do not understand the implications of having a J vs a P. So I’m going to give a foundation on what the letters mean. We are going to do that by starting on the middle two letters.
As you obviously know now, there are four letters.
1 2 3 4
Letter #1 is I/E (Introverted/Extroverted)
Letter #2 is N/S (iNtuitive/Sensing)
Letter #3 is F/T (Feeling/Thinking)
Letter #4 is P/J (Perceiving/Judging)
As a result, there are 16 different personality types.
Now, for this post, forget about letters 1 and 4. Focus, right now, on letters 2 and 3.
Letter 2 is your perceiving function. This is basically how you perceive the world around you. You can either do this in a concrete literal fashion with your five senses which would make this letter an S for you. Or you can do this through iNtuition (N). Intuition uses patterns subconsciously to come to conclusions about things. Sensing ignores what’s behind the scenes while intuition ignores the “external”.
Letter 3 is your judging function. This is basically how you respond or react to what you perceived. You can either do this based on logic and empirical data (Thinking/T) or on something more subjective like your values, morals, feelings, etc (Feeling/F).
Now, to complicate things a little more, these letters can either be extroverted or introverted. The way this is noted is as follows: introverted Feeling (Fi), extroverted Feeling (Fe), introverted Thinking (Ti), etc.
Now, back to the differences between INFP’s and INFJ’s.
INFP’s are very different than INFJ’s because INFP’s primarily live in introverted Feeling (Fi), and then use extroverted iNtuition (Ne). INFJ’s primarily live in introverted iNtuition (Ni) and then use extroverted Feeling (Fe). On the outside, we do appear the same, but once you get to know us, we can be extremely different. I’m going to post more about why this is so in my next post on personality theories.
Andrew Thomasson 
Good blog.
As a fan of ‘personality theories’, this segment of the human experience is like a huge used bookstore, (with all the covers ripped off all the books.)
You can look for general cateogories, maybe decide on a publisher, or scan the first few pages. But it is always an interesting in so many different ways.
There are some amazing blogs on the topic of personality theories. Some are written and done so well, that when I come across them I just want to quietly back out of the site and not look at my own for a while. But then I think to myself, ‘shit, if I were a professional writer, I wouldnt be writing for fun’.
Anyway, good luck with your blog. I invite you to visit mine, I always like to read other blog writers comments.
(www.wakefielddoctrine.com)