Not exactly. A social casino refers to a free-to-play gaming site that has social gaming features. Think player chats, leaderboards, races, etc. A sweepstakes casino is a free-to-play site that lets you exchange virtual credits for real prizes, like cash rewards. Basically, it's a social casino online with real money incentives. Fortunately, social and sweeps casino sites in the US tend to merge both aspects, which is why people use the terms so often interchangeably.