They use largely the same rails/network (for example Mastercard). The only meaningful difference is on how and when funds are reconciled.
Some payment providers ask up front to simplify the flows as it's not totally trivial to determine what sort of card it is, and also because different fees apply - historically some merchants added specific fees to basket etc. (less so nowadays but the UI convention sticks)
Some payment providers ask up front to simplify the flows as it's not totally trivial to determine what sort of card it is, and also because different fees apply - historically some merchants added specific fees to basket etc. (less so nowadays but the UI convention sticks)