I think the difference is: - is energised by interacting with people vs - is de-energised by interacting with people But there is a social skills / anxiety

I think the difference is: - is energised by interacting with people vs - is de-energised by interacting with people But there is a social skills / anxiety aspect to this. Some people aren't particularly inherently energised by social interaction, so will always be introverted. That doesn't mean some social interaction isn't beneficial though - It might mean that they need a lot less though, like how some people biologically need less sleep than others, or degrade slower when deprived of it. Incidentally, I wonder whether "coping mechanisms" are the difference - that introverts develop stronger internal dialogues that substitute for normal (external) social interaction(s).