Is saved progress for family shared games kept in the Steam cloud the same way my owned games?
Another thing, say I bought Elden Ring on Account-A but I want to play it in Account-B, will family sharing it to Account-B and playing it there be exactly the same as actually buying Elden Ring on Account-B?
What is the difference between playing an owned game and a family shared one? Aside from kicking me out of the game because they started playing.
Is saved progress for family shared games kept in the Steam cloud the same way my owned games?
Yes. All users get the same game features for Family Sharing supported games except Trading Cards and In-Game Item Drops.
Another thing, say I bought Elden Ring on Account-A but I want to play it in Account-B, will family sharing it to Account-B and playing it there be exactly the same as actually buying Elden Ring on Account-B?
Yes, as long as the game supports it.
What is the difference between playing an owned game and a family shared one?
Mainly two: Guests don't get Trading Cards nor In-Game Item Drops, and a game or VAC ban on the guest also propagates to the lender.
