A Constant Speed Drive is just that. An input shaft varying with engine speed and an output shaft that is constant speed. The output shaft drives the generator. Usually filled with oil with a pump and a motor, but the BAC111 Spey engine had an CSDS which worked on air!
An Integrated Drive Generator combines a CSD and a generator in one package.
A VSCF is a variable speed generator. No CSD is involved. The frequency wild output is then converted to constant frequency in a box. On the B734 this box was bolted onto the generator, but on the B777 it is in the avionic bay.
Modern big jets all have IDG today. The B777 also has a Back up generator on each engine and a Convertor. Dont know about the A330.