When the hell did we start calling streams "observables"?
https://medium.com/@rakia/promise-vs-observable-vs-stream-16...
The big difference is the pull-vs-push scheme, making Observables lazy-by-default, and just subscribed vs unsubscribed to.
Observable is a theoretical concept in reactive programming, popularized by ReactiveX author Eric Meijer.
It's gained quite a bit of popularity because ReactiveX is heavily used in Java frontends and JavaScript (Angular especially).
There are many others, and then the differences go away.
In fact, Rx can be traced directly to the synchronous dataflow[1] of Lustre[2] and Esterel[3], which in turn goes back to Lucid[4], "The Dataflow Programming Language"[5].
It took a bit to ferret this out of the publication record, but when I asked Erik he confirmed.
[1] https://ptolemy.berkeley.edu/publications/papers/87/synchdat...
[2] https://en.wikipedia.org/wiki/Lustre_(programming_language)
[3] https://en.wikipedia.org/wiki/Esterel
[4] https://en.wikipedia.org/wiki/Lucid_(programming_language)
[5] http://www.cse.unsw.edu.au/~plaice/archive/WWW/1985/B-AP85-L...
But sure enough, if all we care about is a "collection of observed values, asynchronously" 'Stream' and 'Observable' fit the bill in all(most?) implementations.