Less fantasy-oriented, ISFPs are generally more "earthy"; their interests are more likely to involve physically tangible experiences. They often have a natural sense of visual/spacial relations and aesthetics (their homes are frequently uniquely decorated or arranged to make an obvious visual impact), and their awareness of what's current, popular, "in" and so on is often something they pride themselves on.

They give this disarming sense of calm contentedness, almost as if they're too agreeable (and indeed, young ISFP males will sometimes overcompensate for their natural introversion and try to be social supermen), but upon getting to know them you'll find that they usually are some of the nicest people out there. Watching them "perform", in whatever way they may do it, is inspirational. As someone said, ISFPs are known for giving people the fewest reasons to dislike them.

ISFPs are more likely to "cut and run" on an impulse if their freedom or individuality feels stifled by current situations. (I have one ISFP friend who, much to his parents' chagrin, decided after high school to go wander around New Zealand with no particular idea of what to do or where to stay, instead of starting college or a job.)

ISFPs, like any SP type, learn best with a hands-on experiential approach where their natural ability to use tools to manipulate the physical environment will serve them best. They're typically very set in their ethical ways, but are impatient with a lot of abstraction and don't often feel that morality requires a tremendous amount of in-depth analysis--it just comes naturally. Do what you feel seems right at the time, dude!

Both types give really inspired performances when they're into something, but INFPs are typically identifiable by their comparative lack of attention to clothing, fashion and overall physical appearance.

INFPs are basically ethical perfectionists to the point of absurdity, the ultimate idealists. (Like the INTP's obsession with logical consistency, except applied to ethical consistency instead.) You can identify them by their extraordinary attention to moral perfection. If you get to know them, you'll find that they usually exhibit a never-quite-good-enough attitude about virtually everything important to them.

One of the biggest differences is that INFPs hold grudges, and when they dislike someone they're very good at imagining more reasons to dislike that person or picking up hostility from that person when none is really intended (Ne services Fi's ends.) Neither type is openly confrontational, but when ISFPs are offended, they're more likely to just remove themselves from the situation, quit worrying about it and move on the next thing. INFPs dwell.

On the plus side, auxiliary Pe makes them appear outwardly flexible, calm, open, accomodating and generally very open to and respectful of the ideas and feelings of others. INFPs can provide terrific moral guidance, and you can always trust them to remain loyal to their friends and their ideals.

INFPs in a social environment are typically quieter than ISFPs, and much more interested in personal one-on-one conversation than in whatever activities (ISFPs are much more activity-oriented) are going on at the party--video games, sports, drinking games, what have you...ISFPs are more likely to be *doing* something. INFPs are far more likely to suffer from "NP never gets anything done" syndrome, spending too much time dreaming up pie-in-the-sky visions for the future and not enough actually making them happen.

INFPs are more likely to reach for broad, idealistic moral ideals. They're more likely to daydream than ISFPs (who are busy doing real things) and often hold high ideals about change or service toward society in general and how progress might be made. Though typically fairly quiet, if one of these areas of interest comes up they will leap into a conversation and provide often unexpected keen insights and substantial conversation. It's pretty cool sometimes. A stereotypical INFP college major might be philosophy.

INFPs remain outwardly very very chill until their ideals are violated, at which point they will become rigid and inflexible. You're seeing auxiliary Ne most of the time when they're interacting with you, but when some external threat causes Fi to take over, there will be no convincing him otherwise--think INTP who's sure he's logically correct about something. It can be a little silly at times, but a balanced INFP will provide terrific, very personal conversation and companionship.