What's the difference between BNB and BNB smart chain?

I'm curious to understand the distinction between BNB and the BNB Smart Chain. Could you elaborate on the fundamental differences between these two? Is BNB just a cryptocurrency token, while the BNB Smart Chain represents a blockchain platform? If so, how do they interact and what are the key functionalities of each? I'm also interested in knowing if there are any benefits or disadvantages to using one over the other, especially in terms of transaction speeds, costs, and accessibility to decentralized applications. Thank you for clarifying these points.