What is the difference between a wallet and a card holder?

The difference between a card holder and wallet is defined by the functionality. A wallet is a daily accessory to store money, in particular cash, coins, credit cards, ID, and other stuff. A credit card holder is designed to hold specifically credit cards of the standard size. Of course, keeping folded cash or credit cards with business cards in a card holder is up to you, however, you should consider the dimensions of the holder.