While both Cardano and Ethereum make use of blockchains, Ethereum's proof-of-work (PoW) blockchain is currently less flexible than Cardano's proof-of-stake (PoS) Ouroboros consensus mechanism. In order to add blocks to the Ethereum blockchain, you need expensive and high-power “mining machines.” Whereas, for the Cardano network, you only have to stake ADA tokens in a pool to create blocks and validate transactions.