Just to clear first that Ethereum is an open-ended, decentralized, blockchain-based, public software platform that facilitates peer-to-peer contracts, known as Smart Contracts, as well as Decentralized Applications, known as DApps. Other side BNB is the native coin of the very popular cryptocurrency exchange powered by the Binance Smart Chain and regularly draws comparisons to Ethereum, as both coins function in a similar way. But Ethereum is often favored, as it has a higher market cap. Other side Ether have high gas price than BNB makes people think to use BNB smart chain.