The essential difference between ETH and BTC is that in the former you can not only transmit money but also run SC and do DApps. This happens with EVM (Ethereum Virtual Machine), and thanks to the native language of ETH, called Solidity, which is used to write smart contracts and DApps. From there, ETH crypto-currency is used to make these apps and intelligent contracts work.

BTC is developing other tools such as RSK, which is the first open platform for intelligent contracts on BTC, and which remunerates BTC miners by allowing them to participate in the SC revolution. If it works, it could make ETH somewhat less relevant.

The RSK project started as a fork of an Ethereum codebase in 2016 and it was developed for 2 years until it was finally launched in 2018. During those years, crucial data structures were upgraded, and precompiled contracts and new opcodes were added. Since Ethereum compatibility has always been one of the priorities of the RSK community, most changes are invisible to developers and users. When developers look at RSK and Ethereum, they see them as twin brothers.
https://medium.com/iovlabs-innovation-stories/similarities-and-differences-between-rsk-and-ethereum-e480655eff37

Some other comparisons:

  • ETH and BTC entirely differs in its purpose, but both uses Blockchain technology. Net ETH and BTC are formed when adding new blocks to the chain.
  • ETH is a token, BTC is a cryptocurrency. However ETH is now also used in exchanges as currency.
  • ETH focuses on running the code of any decentralized app, and was not designed to become a global currency (as BTC) but to allow payments on specific actions of the participants, in the ETC BTC validating transactions.
  • ETH has UNLIMITED supply, and uses PoS algorythm, not PoW.
  • What BTC does to money, ETH does to contracts (digital agreements to modelize “if this happens, then this happens”)
  • BTC was never hacked. Ethereum has The DAO hacking experience.