Do USD and USDT have more or less or the same thing in terms of the price difference? please suggest because I am planning to buy some USDT.
USDT is a pretend stable coin. It is supposed to be backed by actual dollars, but this is in doubt (no auditor has confirmed the existence of the reserves).
Not sure why you would want to buy it to be honest. USDT just needs one successful investigation (and there are several ongoing) to tank the entire USDT market and send it to zero. Stay clear - either hold real cryptocurrencies (bitcoin, litecoin, ethereum, doge etc) or hold real dollars. Steer clear of the stable coins.