There's a ton of factors besides type that explains such.
Upbringing, social standards/norms, gender, race, other physical differences, others' view of them, etc etc.
If we have someone who is an INTJ, and looks normal and healthy... then we take another INTJ who's identical in every way... but give them a glaringly obvious hunchback... the way people treat them, the way they think of themselves, the way they express themselves, all these things will have drastic changes to them, because of a single physical change which has nothing to do with their brain or mind.
Make one male and the other female; our social standards for both, as well as anatomical differences, will adjust how they behave in certain situations.
Make one live with an abusive, chain smoking, drug addicted, alcoholic tyrant of a single mother as they grow up, and the other in a relatively "normal" caring family. Suddenly their perceptions are vastly different.
They may have the same method by which they process information, but they will filter that information through many different ones applied throughout their lives. Whot do other people think of me? Whot am I supposed to say? How do I get through this without getting in trouble? These questions are often universal, though some mbti types will stress some of them far more than others. Some may not care, others may be more interested in such, but just because yeu have the same question, doesn't mean yeu will assume the answer to be the same.
For some, "whot am I supposed to say?" is vastly different than others of the same type... either because of whot they were taught is 'correct', or to whom they are speaking to.
The factors are nearly limitless.
The only real similarity in MBTI *AT ALL* is how yeu process information. Do yeu think things through to yeurself, or do yeu process information externally by discussing with others? Do yeu notice underlying patterns, or do yeu more readily see the basic facts before yeur face that others may overlook by thinking too hard? Do yeu think things through logically when making a complex decision, or do yeu go with yeur feelings on a whim? Do yeu want things resolved, or would yeu rather keep things open 'just in case' something changes? These are just preferences in thought is all. Yeu can have the same preferences, yet be totally different in the specific details.