How is Tezos different from Ethereum?

Could you elaborate on the unique characteristics of Tezos that distinguish it from Ethereum? I'm particularly interested in understanding the differences in their consensus mechanisms, scalability solutions, and approaches to governance. Additionally, how does Tezos's on-chain governance model differ from Ethereum's, and what advantages does it offer? Also, could you discuss the respective ecosystems of these two platforms and how they differ in terms of developer activity, decentralization, and potential for future growth?