What Is The Difference Between ERC721, ERC1155 and ERC20?

ERC721 is a standard for NFTs that represents unique items, single editions. Each ERC721 token is unique and cannot be replaced or exchanged for an identical item.
ERC1155 is a newer smart contract standard that allows for the creation of both multiple editions (semi-fungible tokens) and unique items within the same contract. Basically, if you want to create multiple copies of your NFT to share with a wider audience, you can use ERC1155.
ERC20 is focused on interchangeable assets with a fixed total supply. ERC20 tokens are typically used for things like utility tokens, security tokens, and other types of digital assets that represent a certain value or utility.