Time has changed. The young Russian boy (only 19 years old by then) was not frustrated by the rejection of the proposal, but turned to develop a platform to realize his own ideas. And this platform is Ethereum.
The biggest difference between Ethereum and Bitcoin is the information recorded on the blockchain. In addition to trading information, Vitalik proposes to record smart contracts in the blockchain to achieve more complex functions. (For an understanding of smart contracts, see the account history article “With a smart contract, reminding friends to pay back the money is no longer awkard”)