The practical differences
- TRC-20 runs on TRON. Transfers usually cost a few dollars or less, and confirm in a few seconds.
- ERC-20 runs on Ethereum. Transfers cost more — sometimes considerably more — and confirm in tens of seconds.
- Addresses look different: TRON addresses start with T, Ethereum addresses with 0x.
- The tokens cannot be sent between networks directly. Moving between them needs a bridge or an exchange.
How to tell which one you have
Look at the address. Starts with T and is 34 characters — TRON, so TRC-20. Starts with 0x and is 42 characters — Ethereum, so ERC-20. Wallets and exchanges also label the network explicitly when you deposit or withdraw; read that label rather than assuming.
Sending TRC-20 USDT to an ERC-20 address, or the reverse, sends the funds somewhere nobody can reach. This is the single most common way people lose money with stablecoins.
Common questions
For a transfer to an exchange, TRC-20 or ERC-20?
Whichever network the exchange itself names on its deposit page. At one exchange the USDT address may exist only on ERC-20; at another, on both. Choosing by price only comes into it when the exchange accepts either.
If ERC-20 is dearer, why is it still used?
Because on large sums the fee stops mattering: $20 on a hundred-thousand-dollar transfer is hundredths of a percent. ERC-20 is also accepted literally everywhere, banks and large platforms included, which is not always true of TRC-20.
How do I tell which network the USDT arrived on?
By the address it was sent to, not by the amount. An address starting with T is TRON, which means TRC-20; an address starting with 0x is Ethereum or a compatible network. A wallet's transaction history names the network outright.
Which to use
For payments and transfers, TRC-20 is cheaper and faster, which is why most exchanges and merchants default to it. ERC-20 makes sense when you need to interact with Ethereum applications, since that's where most of them live.
One caveat specific to TRON: the fee is paid in TRX, not in USDT. Someone holding only TRC-20 USDT often can't send it at all, which catches people out constantly.