I purchased Syberia & Syberia II awhile back ago on Steam but have yet to play either of them, Steam sales are hard to pass up. I am wondering if there is a difference between the versions sold on GOG and those sold on Steam?

Bonus content perhaps?

GOG's versions are of course DRM-free, while Steam's versions can't be run without the Steam launcher.

Syberia 1:
Steam offers a Mac version, GOG doesn't, yet.
Steam supports more languages (Russian, Polish and Japanese)

GOG offers bonus content, as of now:
- manual (9 pages)
- artworks: 16 rendered pictures and 39 sketches
- 7 avatar pictures
- Syberia tracks (6 MP3s)

Syberia 2:
GOG supports more languages (Italian)
GOG offers bonus content, as of now:
- manual (11 pages)
- artworks: 38 pictures & sketches
- 2 HD wallpapers in several resolutions
- Syberia 2 tracks (4 MP3s)
- 6 avatar pictures

GOG's support is better ;-)

Lol, I guess so

2 years passed and there is still no Mac version on GOG :-(

Not a loss from what ive read. It was ported to mobile devices first and the Mac version was supposedly ported from that one and is inferior in several ways. The Win version works pretty well with wineskin though