Ethereum is an innovation network providing its own blockchain with its cryptocurrency (Ether or ETH). This blockchain hosts decentralized applications (DApps) that were first introduced by Ethereum. Another innovation of this platform is the implementation of smart contracts which has changed the perception of the possible use of the blockchain, revealing the potential of the technology to its fullest.
Dash was launched in 2014 and changed several names before becoming Dash as we know it today. The initial goal of the project was to create a cryptocurrency network which would operate faster and cheaper than Bitcoin and would be capable to maintain more privacy. Holders of large amounts of Dash have different privileges (Instant Send, Private Send, etc).
Dash is an open-source project. It has its own blockchain. The currency is supported by many crypto wallets and it has gained significant market capitalization. Another great achievement is its numerous partnerships including cooperations with Western Union, web stores, etc.