Problem is, without the maple block in the body (the main structural difference between the semi-hollow 335 and the fully hollow 330), quite a few of the early 'longer' 330's simply folded up on customers. So Gibson lengthened the neck of the 330, moved the pickups and moved the fretboard on the 330. The 335 proved much more popular, with greater upper fret access. The original 330's (and most of the Casinos, I think) have a lot of the frets buried in the body. There are two 330 models, depending on where the neck is attached.

Assuming you've figured out the differences, here's something else to consider.