Simply put, the BEP-20 standard defines the rules for creating and using fungible tokens (currency) on the BNB Chain. In contrast, the BEP-721 standard defines the rules for creating and using non-fungible tokens (NFTs).
However, the BEP-1155 standard enables the combination of fungible and non-fungible tokens (NFT) in a single smart contract. It enabled the creation of smart contracts that are more flexible and cost-efficient.
BEP-1155 is a multi-token standard for smart contracts that allows developers to combine the fungibility of BEP-20 and the non-fungibility of BEP-721 in a single contract. This means that developers can deploy products that have both types of tokens (i.e., fungible currencies and NFTs) without the need for multiple contracts.
The BEP token standards are adaptations of the ERC standards of the Ethereum blockchain. So, while the ERC token standards define the rules for creating and using tokens on Ethereum, the BEP standards define the rules for creating and using tokens on the BNB Chain ecosystem.
As such, the BEP-1155 standard has the same core functions and features as Ethereum's ERC-1155 standard, but it was designed specifically for the BNB Chain network.
Both 1155 standards combine the best of the other two standards of their respective blockchains: BEP-20 and BEP-721 on the BNB Chain; ERC-20 and ERC-721 on Ethereum.
However, one notable difference between the two chains is the cost. When compared to Ethereum, the BNB Chain offers considerably lower gas fees for blockchain transactions and smart contract deployment.