What is the difference between BNB and BNB smart chain?

Could you elaborate on the distinction between BNB and the BNB Smart Chain? I've heard both terms being used in the cryptocurrency space, but I'm not entirely clear on the specifics. Is BNB simply a digital token, or does it serve a more functional purpose? And what about the BNB Smart Chain? Does it operate independently from the Binance ecosystem, or is it tightly integrated? Could you provide a concise yet comprehensive explanation of the differences and how they fit into the broader cryptocurrency landscape?