The exchange will make it clear what type of chain they are using; however, one easy way to differentiate between these two is by the way the address is structured.
An ERC20 Address only starts with ‘0’ and ‘x’. For example: 0xbc6e.
A TRC20 Address only begins with a capital ‘T’. For example: T9zG21.
Make sure you check carefully before sending a transfer to ensure you are using the right chain address. Do not attempt to send ERC20 based USDT to a TRC20 address or vice versa as the funds could then be unrecoverable.