Originally Posted by shinylatexkitty
to be fair among nonexperts when most people say inear they mean anything that goes in your ear rather than headphones ;P
Who's an expert ... You have two types of in ears in my book.
1) In ear 'non' isolating like the bose, audio technica c7, etc
2) In ear isolating like the shure e530, westone um2, ultimate ears, etc
In general I find type 2) offers much better sound quality but the downside (which to some is a plus) is you don't hear much outside noise so it may not be suitable in some work environments, outdoor activities, etc. I only use an in ear phone from type 1 if it's not practical to use the other kind.
Over ears I only use at home due to my work environment. I can at least pretend the in ears are connected to my phone "and I don't want the phone to ring out loud now do I....)
Over or 'on ears' come in two main types, open back or closed back (again similar to the above). You also have dynamic headphones and electrostatic headphones (for both). (you can get electrostatic in ears from stax too!!!).
In most cases electrostatic offers better resolution of music than dynamic but at a price and you 'have' to have a dedicated amplifier.