Bitcoin and Ethereum both are blockchain-based cryptocurrencies, but they are very different from each other.
Bitcoin is a symbol of value storage in digital age.
Bitcoin is the first cryptocurrency, was developed as a decentralized online payment, but the transaction is very slow.
Bitcoin uses a Proof of Work (PoW) to make sure the transactions are real.
The scripting language used by Bitcoin is restricted to basic transaction types.
Ethereum is developed and run without any kind of control, fraud.
Ethereum is a decentralized blockchain platform which creates a peer-to-peer network so that decentralized apps and smart contracts may be developed.
Ethereum switched to Proof of Sake (PoS), to increase the stability, safety and energy efficiency.
It is a programmable blockchain, which allows the programmers to design complex smart contracts.