Bitcoin is the first ever cryptocurrency that runs on blockchain technology. It is first in enabling individuals around the world to exchange value without the need of a third party (like a bank). In a nutshell  bitcoin is a decentralized distributed database (blockchain), that stores all transactions ever performed and maintains a record of who owns what.

Ethereum is the first ever blockchain that features smart contracts. Smart contracts are lines of code written on top of a blockchain that auto execute transactions, when the conditions outlined in the code are met.

Blockchain technology promises to revolutionize everything from finance and insurance, to data storage, IOT, voting, digital identity and cyber security.

-- Vitalik Buterin, Co-founder of Ethereum. “On a blockchain, you can ultimately build anything that you can build on top of a computer. From a computer science theoretical point of view, in terms of what it provides, you can think about it as being a computer. But what it provides on top of that is these extra trust guarantees: the guarantee that the computer will run in the way that you expect it to run, and that a few people can’t make that guarantee fail by going out of business, getting hacked, dying, having their company go bankrupt, deciding to be evil one day, deciding they have some monopolistic interest to start acting differently one day, and all of those different issues.”