BNB Smart Chain and Ethereum offer alternative approaches to the development of decentralized finance. The first way is centralized and fast. The second is decentralized, slow and expensive. So, on Uniswap exchange and on Ethereum blockchain, you need to pay about $30 fee to conduct a trade.
Ethereum leads the DeFi sector. Blockchain faced the problem of scalability, therefore, it cannot fully satisfy the hype around decentralized finance. Along with it, BNB Smart Chain offers lower fees, which attracts users to the Binance blockchain.
BSC is a centralized blockchain environment that Binance is responsible for maintaining. Other than that, BSC has only a handful of successful projects (which are copies of Ethereum projects). While Ethereum is a decentralized ecosystem with thousands of independent projects.