What is the difference between US and RU cards?

Question

Payment cards

Here is VISA/MASTERCARD RU and there is US.
When I pay, for example, on namecheap in dollars from RU cards, the rubles themselves are converted into dollars for purchase.
And for example, when I want to donate to donationalerts in dollars, then from RU I can only donate rubles and from US only dollars.
why?

Answer 1

donationalerts apparently made a ban on ruble payments from us cards

Answer 2

apparently it depends on the bank that issued the card and processes your payments, and on the service that accepts card data from you and addresses them to the bank. IMHO