Ethereum and Monero are two different crypto currencies. Monero is a cryptocurrency just like Bitcoin whereas Ethereum is platform to run smart contracts. Monero is more private and fungible than Bitcoin. It has a friendlier community. Many people see Monero as the next Bitcoin. Ethereum as a platform gives ability to develop apps over the platform. You can develop your private currency over the Ethereum platform. In very basic terms, Monero is a currency like Yuan and Ethereum is a platform like Android. Both are good projects.