There are two Ethereum smart contracts pre-deployed by Rarible and are useable by anyone on the platform.
Each collection type represents a smart contract, either ERC-721 or ERC-1155. Single NFTs get created under the first standard for Non-Fungible tokens– EIP-721. (Ethereum Improvement Proposal)
On Rarible, Multiple NFTs get minted with a token contract based on the implementation of EIP-1155.
ERC-721 (Single NFTs)
This excerpt is directly from EIP-721.
"A standard interface for non-fungible tokens, also known as deeds."
The proposal created a standard for non-fungible tokens. Specifically, at the interface level. Meaning– a formal design got created and implemented for everyone else on Ethereum to follow.
The design of which allows for a broader acceptance of standard functions and principles of design. Standards lead to an increase in throughput and user-friendly use-cases for the Ethereum network.
At the time, the standard proposed creating basic functionalities for the tracking and transferring of unique tokens on Ethereum. ERC-721 intended to create structure and order. Now, that standard has evolved into more compelling use cases such as CryptoKitties and Rarible's Marketplace contracts.
Here is the Smart contract, viewable on Etherscan.
0x60F80121C31A0d46B5279700f9DF786054aa5eE5 – ERC-721 (Single NFTs)
Click here, for all NFTs minted on Rarible under the 'Singles' Smart contract.
ERC-1155 (Multiple NFTs)
Directly from the EIP-1155.
"A standard interface for contracts that manage multiple token types. A single deployed contract may include any combination of fungible tokens, non-fungible tokens or other configurations (e.g. semi-fungible tokens)."
In short, as the industry evolves, new standards get proposed. It is similar to building codes. Old buildings do not become redundant because of updated or renewed standards. Instead, we complement our existing ideas with concrete advances and innovations of previous models.
EIP-1155 proposed a standard interface for managing multiple token types with a single contract. Instead of creating individual contracts for each asset, the 1155 contract can create new assets or additional assets underneath itself with different properties. The ERC-1155 contract is also more efficient than the ERC-721 contract– concerning gas optimizations.
Here is the Smart contract, viewable on Etherscan.
0xd07dc4262BCDbf85190C01c996b4C06a461d2430 – ERC-1155 (Multiple NFTs)
Click here, for all NFTs minted on Rarible under the 'Multiples' Smart contract.