Polkadot offers better scalability than the ethereum blockchain. It offers relay chain, cross-blockchain features, forkless network, decentralized governance and all these are not available in the ethereum network. Actually, Polkadot offers all the solutions to those problems that the ethereum network can not. So many projects are using the Polkadot network. Do you think Polkadot is really Ethreum killer?
This is the first time i have check their website about their mechanism and what is the major difference between the two even though i have seen this name in exchanges but after going through their governance it looks promising and lets see how how both will compete against each other.