Different networks may require unique identifiers for deposits.
EOS and USD
A deposit memo is a unique identifier included in an EOS or USD transaction, used by Bullish to distinguish one customer’s deposit request from another.
The reason these deposit memos are required for EOS and USD, and not BTC for example, is due to how the respective network’s account/address systems work.
For EOS and USD deposits, all customers deposit to a single account. These unique memos allow Bullish to identify and credit the correct customer with the right deposit.
The unique identifier for the Ripple network (XRP) is called the destination tag. This is used to distinguish each customer's deposit.