The Main Difference Between Money and Currency

Currency is everything that money is except for one big difference. Currency is not a store of value over time. In 200 years, the current US Dollar will probably be worthless or worth much much lower in value than it is today. Whereas, you take a gold coin today and it will absolutely be valued something in 200 years.

Since both a US Dollar (or any other fiat currency) and a gold coin can be traded for something else today, there are both considered currency and money. The difference is that the US Dollar will lose its value over time. Whereas gold is very much unlikely to lose its value value in time.