I have been playing bass off and on for several years now, but on borrowed basses. I got into playing more or less by accident so I haven't done much homework on the different types of basses. I was given a Squire Bullet Bass, (ok, I've read the posts so lets not go there) and have a question about the different types of basses. So, what is the difference between a P-bass and a J-bass? Also, in the 4-string basses, is there a difference in the necks?