Whats the difference?

Creation Club mods of varying quality. Some of it is good, some of it is kinda game-breaking, but they are all "official" Skyrim content at this point just like the Plug-ins for Morrowind and Oblivion. Depends how much a purist you are about the game. Other people swear by non-official mods that do some of the same things better. Is there $14.00 worth of content in there?? I would say so. But your mileage may vary.

The thing is 4 of the Creation club mods listed are things which were made available to special edition owners on steam for free (downloaded via creation club).

They were things like the survival mod, fishing, saints and sinners and another one I can't remember.

If they aren't in the installers GOG are providing, without creation club support there is no way to get them without purchasing the upgrade.

My worry is if they aren't included in the GOG install it might actually break save file compatibility when transfering from steam to GOG. There isn't any mention of it on the store page either way.

so basically its all just about mods. If I buy anniversary I get 74 mods for free, right?

No. The AE costs more, and that is for the knick knacks that come with it.

but those "knick knacks" are only mods?

http://www.gogdb.org/product/1801825368

http://www.gogdb.org/product/1801825368#references
http://www.gogdb.org/product/1162721350#downloads
http://www.gogdb.org/product/1711230643/build/55846306920288567

and files list itself (can be differ a little bit for offline ver GOG build)
http://www.gogdb.org/manifest/e3233e59beec9478e2b2933be369742d

Hmm, 140 files and 70 mods listed here
http://support.gog.com/hc/en-us/articles/6852264113309-The-Elder-Scrolls-V-Skyrim-Anniversary-Edition-Creation-Club-content?

Hi! Are GOG versions better than versions on STEAM?

Yes. Mostly weapons (like elemental arrows). Except for the fishing rod. I think you get it for free in SE.

Given that you own the game and so can still play it if your pc is the last copy of it with it in the post apocalyptic future, I would say yes by mileage.

That is unless you want to play with any of the mods that were specifically made for the pre-AE build (1.5.97) which can can still be downloaded and played through Steam - but currently isn't (and probably will never be) available from GoG. Quite a few mods haven't even been updated to the most recent Steam version of the game yet and the GoG version is yet another build.

So pick your poison. You either 'own' your game and miss out an some of the best mods or you don't own your game but get to play those. Don't know, maybe if you're playing on linux exclusively or something... Can't really recommend the GoG version to anyone else, though.

I'll just make it short and sweet: didn't like anniversary upgrade. uninstalled everything and did a fresh install of good old regular game and started over !

+1. This line really struck me as important to quote (re-iterate)... the very crux of GOG's model.

Note, and this was news to me since it's confusing AF, that if you buy the Anniversary Edition, you also end up with the Special. Anniversary is actually presented as a DLC.

So you may just buy the Anniversay "in case you like it", and still have the vanilla one.