I think the other two did a pretty good job. Here's my view
Calvinists---adherence to TULIP. There are calvinists in several denomininations--baptists, presbys, some charasmatics have the biggest percentage. Not too many calvinists in the methodist, catholics, etc. Calvinism is a belief in the total soveriegnity of God, which can be applied an any denomination pretty much.....
Baptists---biggest difference is in the baptism practice, but I think heavens bride hit the nail on the head as to why it's different. Most baptists seem to be pre-mill in their eschetological views and dispensational rather than covenental(and as she mentioned, the covenental beliefs are a bit different also)
Presby's---sprinking baptism, infant baptism, alot of amillenialists, mostly coventental(I actually don't know of any dispensational presbys now that I think about it.....), and as far as I know all are calvinists(can you be presbyterian and not a calvinist? somehow that doesn't seem possible)
Oh, another difference is type of worship. Presby's seem to be more formal in worship and the musical worship is more traditional in style---and baptists aren't as formal and unless they are the type of baptists that don't believe in "musical worship", they use contemporary praise and worship music and "praise bands".
Hope that helps. Seeing as how I'm not presbyterian, if I messed anything up, someone inform me!!
