In short, it can be safely converted to either of them

What is the difference between the two digital currencies USDT and USDC?

Certainly, here is the difference between the two digital currencies USDT and USDC:

Both are stablecoins pegged to the US dollar, aiming to maintain a stable value of 1 dollar per unit. However, there are significant differences between them:

USDT (Tether):

Issuer: Issued by Tether Limited.
Transparency: USDT has faced criticism due to a lack of full transparency regarding the reserves backing the currency. Although it issues attestation reports, it has not undergone regular full audits.
Regulation: There have been some concerns regarding Tether Limited's compliance with regulations and laws.
Liquidity: USDT is considered the most liquid stablecoin with the highest trading volume in the cryptocurrency market. It is widely available on most trading platforms.
Usage: USDT is regarded as the most commonly used stablecoin in trading among various cryptocurrencies.
USDC (USD Coin):

Issuer: Issued by Circle in collaboration with Coinbase through the Centre Consortium.
Transparency: USDC is more transparent as it is subject to monthly independent audits by major accounting firms to confirm that every token is backed 1:1 by US dollars or equivalent high-quality liquid assets held in regulated financial institutions in the United States.
Regulation: USDC has a good reputation regarding regulatory compliance.