Qtum is a cryptocurrency that combines the security of Bitcoin's blockchain model and the flexibility of Ethereum's smart contracts. It uses a proof-of-stake consensus model for creating new blocks, which is far easier and less energy-intensive than Bitcoin's proof-of-work model.This makes Qtum more environmentally friendly than other cryptocurrencies. Qtum also has a built-in governance system that allows users to vote on proposed changes to the protocol. This makes it more decentralized than Ethereum, which is controlled by a small group of developers.