What is the relationship between Bitcoin, Ethereum and blockchain?

Bitcoin? Have you heard?
Blockchain? Have you heard of it too?
Ethereum? Is it like a tofu shop?
That's right! Ethereum is the "Tofu Square", but the output is not tofu, but applications!
A brief introduction
to popular science: Bitcoin is a decentralized electronic digital currency. It is a virtual currency for breaking through national borders, trading platforms, and trading currencies to realize unconstrained transactions. The bottom layer of Bitcoin is realized by blockchain. It is a product of blockchain 1.0!
Ethereum also has the purpose of virtual currency, but more importantly, it is a platform that provides various modules to facilitate users to build a decentralized and non-ownership platform for applications. This application is precisely a smart contract. When a user sends an ether transaction to a smart contract, the contract executes business logic based on the transaction amount and information to implement the business. The core of Ethereum is currency and decentralized programs or contracts, which is blockchain 2.0!
My understanding can only go so deep. If you have a researcher, you are welcome to take a dive...