I know steam is drm and gog is free, but still there is a huge difference in price between the two versions.. are there any other mayor differences in both platforms??

GoG SS4 Deluxe - US$17.12
Steam SS4 Deluxe - US$49.99

any ideas?

For me it's the same price like on Steam.

man is 30usd more expensive on steam

Seeing $49.99USD on both sites and I'm in the US. No version of the game is below $20USD that I can see.

thats interesting, I'm in Dominican Republic and the price I have in GoG is 17.12USD.