Like the BEP-20 token standard, BEP-721 defines a set of standards for which the value of a token is defined and differentiated.
Unlike BEP-20, BEP-721 tokens are non-fungible; each and every BEP-721 token has its own unique value and is to be treated individually.
Think of currency: for example, each BEP-20 token can be compared to a $5 bill where you can exchange one $5 bill with another $5 bill without any difference in value. In the case of BEP-721, think of the example of Pancake Bunnies. Each bunny is different in value, has individual traits, and is often treated as a collectible.
A list of BEP-721 Tokens is available on BscScan.