A Wallet ID is a unique number generated for your wallet. It will identify your Wallet in the blockchain network. The ID consists of 36 symbols, which are divided by dashes. Example of ID: 7a6ffed9-4252-427e-af7d-3dcaaf2db2df
From the user's point of view, the wallet address is more important (and frequently confused with the ID). That is a code, which is generated for receiving payments. It consists of 25-36 symbols. Example of address: 1ExAmpLe0FaBiTco1NADr3sSV5tsGaMF6hd
Your cryptocurrency will be sent to this address.
Every time you click on it, the Wallet will generate a new address for you. You can use the newly generated address, or you can save one of the generated addresses and keep using it. All of the generated addresses are valid and you can use any of them receive cryptocurrency in your Wallet.
Most Wallets are made exclusively for one currency. Due to this, it is necessary to have different Wallet for each currency.
Alternatively, there are multi-currency Wallets. With these wallets, it is necessary to be cautious about the “section” (currency) you use to you generate the address, as there are differences among them. For example, if you generate an address in a Litecoin "section" of a Wallet and you make a Bitcoin order, Bitcoins will not be received by the Wallet. Always make sure and confirm that you are providing an address connected with the appropriate currency. The easiest way to understand how a multi-currency Wallet is to imagine that there are several Wallets for different currencies simply connected into one app.