There are a few key differences between Tether (USDT) and USD Coin (USDC):
1. Issuing entity: USDT is issued by Tether Limited while USDC is issued by the Centre consortium.
2. Collateral: USDT claims to be fully backed by reserves of traditional fiat currencies, such as the U.S. Dollar, while USDC is backed by deposits of U.S. dollars held in bank accounts.
3. Transparency: USDC has undergone independent audits to verify that it is fully backed by U.S. Dollar deposits, while USDT has faced controversy and criticism over its lack of transparency and its ability to demonstrate that it is fully backed by reserves.
Both USDT and USDC are popular stablecoins widely used in the cryptocurrency market. However, USDC may be perceived as having greater transparency and trustworthiness.