What exactly are the difference between BTCUSDT, BTCUSD, and BTC/USD?

I use tradovate to trade and i want to dabble into the crypto markets. Mainly because of liquidity and personal time reasons. i work full time and only WFH on some days. I usually trading futures but on the days that i'm not working from home, i want to be able to trade crypto after hours since futures have very little liquidity then.

I've paper traded BTCUSDT and it's been pretty fun seems fairly liquid. But i'm kind of confused. Tradovate has BTC/USD. But tradingview has BTCUSDT and BTCUSD. Someone said BTCUSDT is more liquid. i'm just curious as to what the difference is.

tradovate requires you to pay $10 a month to connect tradingview to it and i'm wondering if i should. but if BTCUSDT is more liquid and better to trade, i'd do that. just need some thoughts on it.

What exactly are the difference between BTCUSDT, BTCUSD, and BTC/USD?