The difference is in the purpose of the each cryptocurrency. Bitcoin was made with the main purpose to became globally accepted payment method, where people will be using Bitcoin in order to buy goods and services. Bitcoin was first cryptocurrency ever so it is more widely popular than Ethereum. Ethereum can be observe as a platform very similar to a supercomputer.
Also, probably the most important difference is the way how people are using the blockchain technology. In Bitcoin case it is strictly using blockchain through exchanges like Coinbase, Ethereum have some features which Bitcoin does not have. Ethereum offering to its users to develop their own ideas, projects, applications and get funded through Ethereum\'s currency Ether. Another difference is Initial Coin Offering or shortened ICO. Again there is opposite effect to Bitcoin and Ethereum. As we already said, Bitcoin was first cryptocurrency ever, so every new cryptocurrency can be traded for fiat money or for Bitcoin and this is the effect how ICOs influence to the value of Bitcoin. Ethereum is a ledger technology more advanced than Bitcoin\'s.
Ethereum is well known through its smart contracts. Smart contracts are method of automating complex business applications which are much safer and more profitable than those which are based on Bitcoin. Some of the biggest companies had a mutual agreement through the Ethereum\'s smart contracts, it is an alliance called Enterprise Ethereum Alliance. Ethereum\'s transaction time is lower, this is making its practical to use and it is another advance in comparison to the Bitcoin\'s very high transaction time.