So if person A has USDT on Ethereum and person B on Tron, basically those are 2 different tokens a d person A cannot send Tether to person B?
Ethereum and TRON are different blockchain.
Tron used the different sha than Ethereum. That's why you need to send your ethereum USDT to the exchange site that support USDT TRON and then you can convert your USDT ethereum to the USDT tron easily. This is the best way to send person B USDT tron. This is not so complicated but what you need to register on the exchange site like binance to be able to do that.
Exchange site is supporting all of USDT assets like ethereum, TRON or even BSC.