Ethereum has been a great innovation in blockchain technology, so much so that it has been defined as blockchain 2.0.
The main difference with Bitcoin is the possibility of programming applications on it.
These applications, called dapps, can perform the most varied functions: decentralized exchanges, wallets and so on.
Ethereum started as a POW consensus mechanism and the transaction fees became very high.
Because these fees provide the energy, or power, to run applications on Ethereum, these fees was also called “gas”. In september 2022 Ethereum made an historichal swith to the PoS consensus mechanism, but up to now the gas fees are still high.