Is arbitrum and Optimism the same?

Excuse me, could you clarify something for me? I've been hearing a lot about Arbitrum and Optimism, but I'm not entirely sure if they're the same thing. Could you explain the difference between them, if there is any? I'm particularly interested in understanding their roles in the cryptocurrency and finance world, as well as any distinct features or advantages they might offer. I'm trying to wrap my head around this complex field, and your insights would be greatly appreciated.