It looks like people have been buying games in other countries, and then playing them locally on Steam. It's not hard to do, a simple VPN from the UK to the US, and I can buy my games in USD, and have access to the US inventory, then play them in the UK.
From this post and it's comments I'm guessing people were using similar ideas to VPN into Russia, get cheap games, and then play them in their native country/language.
Long story short, this looks/feels/smells like game manufacturers and Steam trying to make sure people pay full price for games. (no judgement, just stating they're trying to maximize revenues)
I would imagine in most cases the games are the same, though in certain locations (Germany) I would guess that the content might be edited based on Germany's watchdog restrictions. This might also be to broaden the market into countries that have more restrictive content managed systems.
All best guess, and IMHO, hope that helps!