This is a very common interview question that asks in angular so if you want to can explain this with example then the interviewer .You can go through my article there u can get to know about it with examples.Below is the link of it.https://www.c-sharpcorner.com/article/what-is-the-difference-between-observable-and-promise-with-example-in-angular-8/
A Promise handles a single event when an async operation completes or fails.An Observable allows to pass zero or more events where the callback is called for each event.