Nah there is no difference between BUSD and USDT.. Both are stable coins but I prefer USDT because of course this coin is the most popular of all stable coins and it seems most exchanges has USDT while BUSD listed only in Binance Exchange I guess.
Usages wise both are stable but like what you have said USDT can be used to more exchange compared with BUSD, with the same purpose you'll be better to go with coin that you can transfer from exchange to exchange.
As much as I mistrust USDT, they have more trading pairs and a lot more liquidity than the BUSD. That makes it more practicable for trading
Same thing, you can use USDT to convert your asset and transfer it to another exchange if you are seeing any potential
coin to divert your money.