Simple. Check 21 is an act passed in United States legislation. It was voted on and passed and is now a legal part of the United Stated financial system. Kind of like an ammendment like the Right to bear arms.
Visa and Mastercard are credit card COMPANIES. Mastercard had an IPO last year (I think it was) so they are now a publically traded COMPANY. Visa, I think, is still private, but I have seen talk about them doing an IPO (Initial Public Offering) to become publically traded as well. Maybe they have already, I wasn't really paying attention. Anyway, to be traded publically or to be a private COMPANY, means you have some kind of PRODUCT. It is a PRODUCT that is sold for a price which generated revenue.
In summary, policy is on paper. It is a protocal that has been approved by congress or whtever governing body. It is more of a rule than a tangable asset and it is specific to the United States of America. It has no price tag.
a product is a tangeble item that can be bought and sold. It usually serve a needed purpose in which peole are willing to pay money for.