Underneath "trc20 vs bep20" sits one idea: the coin is the same, the road it takes is not. USDT TRC20 is the version of USDT issued as a TRC20 token on the TRON blockchain, and it is one of the most common ways to send USDT because fees there are usually low. The same coin also exists as BEP20 on BNB Chain and as ERC20 on Ethereum. Each version has its own fees and rules, and a balance on one network never moves to another by itself.
TRC20 vs BEP20 is mostly a question of chain and fee coin. TRC20 runs on TRON and pays its fees in TRX or through energy and bandwidth; BEP20 runs on BNB Chain and pays them in BNB. Both are usually cheaper than Ethereum. Which is cheaper at a given moment depends on network load, the resources an account holds and the withdrawal charge an exchange adds. TRON addresses begin with T and BEP20 ones with 0x, yet the network should still be picked from the list at both ends.
TRC20 vs ERC20 sets TRON against Ethereum. ERC20 fees, paid in ETH gas, are often far higher when Ethereum is congested, which is why many people prefer TRC20 for small USDT amounts when the receiving side supports it. Support is the deciding detail: some platforms accept only one of the two, and some take a network for deposits but not for withdrawals, so each page needs its own check. On any route used for the first time, sending a small amount before the full sum proves that the network matches.
What is the ERC20 network? ERC20 is the token standard on Ethereum, and the ERC20 network is the everyday shorthand for sending such tokens on Ethereum. USDT ERC20 is the version of the coin issued under it, and many exchanges support it. Its fees are paid in ETH as gas: the gas a transfer uses multiplied by the gas price at that moment, which can climb sharply when Ethereum is busy. A wallet the owner controls usually needs some ETH to send ERC20 tokens at all, unless a service sponsors the fee or another party pays it.
Ethereum and compatible chains share the same address format, so one 0x address can exist on both while the balances on each stay separate.
ETH, as gas: the gas the transfer uses times the gas price at that moment, which rises when Ethereum is busy.
Its network list for sending and receiving should name TRC20 or TRON explicitly; supporting USDT alone says nothing about the network.
BNB, the native coin of the chain, so a wallet sending BEP20 tokens needs a little BNB.
In energy and bandwidth, from resources the account holds or has been delegated; when those run short, the network burns TRX to cover the difference.