How does Ethereum 2.0 work?

Could you please elaborate on the mechanics of Ethereum 2.0? How does it differ from the original Ethereum blockchain? What are the key changes and improvements introduced in Ethereum 2.0? How does the transition from proof-of-work to proof-of-stake affect the network's security, scalability, and energy efficiency? Additionally, what role does staking play in Ethereum 2.0, and how does it benefit validators and the network as a whole?