I like your analogy between the cryptocurrency and the universe of Internet.
I suggest another form of comparison: with language.
The blockchain is the language itself; it is a system of writing and speaking (the protocol), say, English language.
Bitcoin is the newspaper. It is an application of the language for communication (transaction). A popular, but ancient form. Slow. And paper and ink getting more and more expensive (tx fees. LOL)
Eth also speaks in English (blockchain technology), but use another form of language that more suited for legal affairs (the smart contract concept). It still a way of communication (transaction).
Steem - computer programming language. Advanced, open, fast, for the future.