Crazy_McGee: I can't speak to the specific differences between the GOG and Steam versions but, there is one key difference that is shared by all games currently on GOG:
Offline Installers.
Every game purchased on GOG comes with an offline installer (in the Extras tab on each game's page in the Library section). This means that the game can be installed without an Internet connection; it can be stored on a hard drive, DVD /Blu-Ray and thus contains no* DRM. (Requiring Steam to run all purchased games is DRM.)
The largest downside of GOG is, as you have elduded to, its update schedule. Steam is an order of magnitude larger than GOG so the desire to upgrade games on the platform is not as high on developer's list as the Steam version. That said, the updates are getting better with every year; for a large number of games (especially the indie / retro-modern titles) the updates occur at the same time!
The biggest difference I've found is when you download on steam, thrones on steam seem singular part as a whole, I've gotten ascension from there but not much else as I only loaded the minimum of the balances available to load at a time, it didn't download offline; although I'm almost sure the games option is there I just used Hotspot to get it. Now Skyrim being a bigger "parts as a whole" game I naturally thought it would download all at once, not knowing the parts required seperate download/install. I'm stuck at 7/8 and I deleted all the so called copy lies I thought it wouldn't needs there a way to download as a whole single download on gog or is it always a part as a whole type download on their website
