While coins exist on their own blockchain, multiple tokens can be created on an existing chain saving the developer time and money.
At a foundational level, coins and tokens offer some similarities in representing value and enabling payment processing: coins can be swapped for tokens, with the reverse also holding true. Where differences become apparent is in their utility. Most cryptocurrency coins typically operate as a native coin on the blockchain as a store of value, while tokens typically exist for use on a decentralized application (DApp). Since tokens are created on existing blockchains, many project tokens may exist within the same ecosystem, most of which can be migrated as needs change.
