There are some basic differences that we can easily recognize:
- BTC is number 1, ETH is number 2

- Bitcoin uses POW, while ETH is about to be transferred via POS;
- It is difficult to program an application based on Bitcoin, but very easy on Ethereum;
- BTC is oriented to become a means of payment & storage of assets, while ETH is a utility token on the Ethereum network;
- Bitcoin uses Lightning, and Ethereum uses Shardings & Plasma extension solution;
- BTC founder Satoshi Nakamoto is anonymous, and ETH founder Vitalik Buterin is famous.