Credit Card Networks: Visa vs Mastercard vs Amex vs Discover
Network vs issuer
The network (Visa, Mastercard, Amex, Discover) routes the transaction and sets acceptance; the issuer (Chase, Citi, Capital One, and so on) lends you the money and sets the rewards. Visa and Mastercard only run networks, so banks issue cards on them. Amex and Discover are unusual in being both the network and, usually, the issuer of their own cards.
Acceptance differences
Visa and Mastercard are accepted almost everywhere cards are taken, in the U.S. and globally, which is why they are the safest choice for international travel. American Express acceptance in the U.S. is now very broad, but it lags overseas and at some small merchants because of higher fees. Discover has the narrowest acceptance, especially abroad. Carrying a Visa or Mastercard as a backup when you travel is smart.
What it means for you
Rewards and most benefits come from the issuer and the card tier, not the network, so a Visa and a Mastercard from the same bank can be nearly identical. The network mainly affects where the card works and a baseline set of protections (see Visa Signature vs Infinite and World Elite Mastercard). For acceptance abroad, also check foreign transaction fees.