Although Bitcoin and Ethereum are both based on the decentralized blockchain architecture which has no middleman, Bitcoin is strictly a cryptocurrency. All transactions pertain to buying, selling and transferring the coins.
Ethereum's cryptocurrency (Ether) can also be bought, sold and traded like Bitcoin. However, in addition to its own crypto, Ethereum is a general-purpose platform that hosts other cryptocurrencies in the form of tokens as well as "smart contract" applications. See smart contract
Both cryptos are having a major impact on the world, but for different purposes. Bitcoin is entirely unregulated cash. Ethereum is also unregulated cash but so much more because there is a fee for every smart contract transaction. As more smart contracts are deployed on Ethereum, the more Ether is paid to operate them. Ethereum is even called "the world computer," as dramatic as that sounds. See blockchain oracle
Cryptocurrencies and Tokens
Although Bitcoin is the only asset on the Bitcoin network, there is no end to the types of assets on Ethereum. See Ethereum token
Cap and Speed
The number of Bitcoins will eventually top out at 21 million in the year 2140. Ethereum has only an annual cap of 18 million Ether.
A new block of Bitcoins takes up to 10 minutes to become part of the blockchain. Ethereum blocks take only seconds. See Bitcoin
, crypto glossary