I have been thinking about getting Fallout 2 but I have a quick question. What are the differences between the Retail CD (US version) and the GOG version? I've read a similar thread for Fallout 1 (which I am also considering) so I have a general idea of what to expect.

No big differences I'd guess. GOG version uses minor text changes like the UK version (e.g. 'drugs' became 'chems'). It could be that children in the vanilla GOG version are missing, too, but as I'm playing with Killap's Restoration Project installed, which adds all this content, I'm not sure.
As far as I know the US CD has no copy protection, but not sure about that either - GOG is definitely DRM free.

Thanks for the info! I decided to go ahead and get the GOG version.