i'd say this is actually a good topic. i have an INFJ friend that sometimes looks very ENFP.
i'm going to get off the boat on this because being an ENFP i don't have external perspective on this issue, but the main differences i notice between my friend and myself are that she's more social (Fe), as in she always organizes things for friends like dinners etc but when she's in trouble she also wants all her friends to participate/help her as a group - i don't do that, i don't usually entertain because my house is my personal space more or less and if i'm in trouble i recoil back to myself and maybe see friends one on one.
similarities, i notice we are both perceivers, as in non-judging.
what else?...ah, i normally blurt out things. while she when speaking can have extended moments of silence, like if she was thinking, and then will come up with something constructed and definite (i guess this is Ti?)
lastly, she has told me and i've noticed that she has problems understanding her own emotions. i find this weird, i'm the opposite.
also, she's like a social butterfly, always out of the house doing stuff. and when she's in her house she keeps it pristine and likes to create an environment that reflects her inner state. but then she's also an introvert and you can see she places a big gap between social world and innerself. for instance, she hides her emotions from you often, and you feel there is a disconnection there between the outer world and her inner world (Ti wall?)?
i'm the opposite, i'm not jumping around all the time and i don't care what my house looks like, i just need a place to crash. also, i can share my emotions and talk about them and i like going to the bottom of things.
i hope i didn't create more confusion than before. this is just an improptu outlook on what i experience, but i'm not sure if all i said fits with being ENFP/INFJ or whatever.