$USDC is a stablecoin designed to be pegged to the US dollar and redeemable at a 1:1 ratio for US dollars, backed by dollar-denominated assets held in segregated accounts at regulated financial institutions in the United States.
The #tetherUsdt is a stablecoin that is part of a type of cryptocurrency designed to be more stable than other cryptocurrencies, as they are backed by assets such as the US dollar or gold.