ERC-1155 is a digital token standard created by Enjin that can be used to create both fungible (currencies) and non-fungible (digital cards, pets and in-game skins) assets on the Ethereum Network. By using the Ethereum network, ERC-1155 tokens are secure, tradable and immune to hacking.
ERC-721 is a free, open standard that describes how to build non-fungible or unique tokens on the Ethereum blockchain. While most tokens are fungible (every token is the same as every other token), ERC-721 tokens are all unique. Think of them like rare, one-of-a-kind collectibles.