While tokens are built on an existing Blockchain platform, representing assets or a utility, coins are cryptocurrencies which have their own platform and exist independently.
They are the native currency of their own Blockchain. Bitcoin is the original cryptocurrency, so others are also called alternative coins or altcoins.
There are two types of altcoins. Some, like Dogecoin and Litecoin, are created through modifications of the original Bitcoin source code. Others, like Ethereum and æternity, have developed their original independent new Blockchains.
In general, coins are considered the foundation of tokens as a medium of exchange, but the latter can be used for different purposes like representing ownership or providing voting rights in a blockchain project.