The Main Interface and the Interoperable Interfaces
All the Items have the Main Interface and an Interoperable one.
The Main Interface is the same for all existing Items, native or wrapped, and so all the Items share the same Main Interface address. The Main Interface acts as an ERC1155, so you can use it when an Item needs to be used as an ERC1155 or interact with an ERC1155-based protocol or application.
Every Item also has its specific Interoperable Interface, and so at each Item id corresponds an Interoperable address. You can use it when an Item needs to be used as an ERC20 or interact with ERC20-based protocol or application.
Benefits of having two "faces"
Having two faces (Main Interface as ERC1155 and Interoperable as ERC20) is the true power of a single super-standard that can be used in every Ethereum Dapp by users and can be integrated by every developer in their application without any issues to build items on Ethereum.
All the Items' information are stored in the Main Interface contract, such as the total supply, the balance of a specific address or the name, symbol, and uri of a specific Item, and so on.
Even the Interoperable Interface writes and reads directly on the Main Interface storage when functions on the Interoperable Interface are called.
By the way, as said before, both the Main Interface (ERC1155 version) and Interoperable Interface (ERC20) can be used independently from each other.
The Main Interface and Interoperable Interface facades standardly have 18 decimals making it extremely easy to integrate Items into Dapps, even at the Frontend level.