Anecdotally, the ISFPs I have known have differed from INFPs in that INFPs seek some form of self-discovery and to know or understand themselves on a deeper more meaningful level and have considered mbti to be a vessel for that. ISFPs on the other hand, have a greater tendency towards stating that you can't put them in a box and would likely feel that mbti does just that and would therefore avoid it.

I totally agree with this. My best friend is ISFP and for a long time I couldn't understand why the hell don't they seek self discovery at the same level.

I know a lot of ISFPs because I'm studying visual arts (yes, the stereotype is true), and they seem to be almost 100% focused in the fucking drawing, in the canvas, in handy activities as their default. They doodle in class when they're in autopilot while I think about my inner self or some philosophy and usually write about it.

Today I was talking with my ISFP best friend and he doesn't have a diary, which sounds ridiculously strange to me, but they do not usually have one, or at least not the ones I know.