1. Blockchain - cryptocurrency.
A cryptocurrency coin is one that has its own blockchain.
Examples include Bitcoin, Litecoin, Etherium and Ripple.
Contrasted with tokens, which do not have their own blockchain.
2. Currency - money - small denominations.
Small denominations of physical money, made of low-cost metals or other low-cost material.
3. Currency - collectable - investment.
Investment coins made of precious metals, usually gold.
Some have a nominal face value, but the market price greatly exceeds the face value because of the precious metal content.
Examples include the American Gold Eagle, South African Krugerrand and British Sovereign.