Observables vs Promises

Both Promises and Observables provide us with abstractions that help us deal with the asynchronous nature of our applications. However, there are important differences between the two:

• As seen in the example above, Observables can define both the setup and teardown aspects of asynchronous behavior.

• Observables are cancellable.

• Moreover, Observables can be retried using one of the retry operators provided by the API, such as retry and retryWhen. On the other hand, Promises require the caller to have access to the original function that returned the promise in order to have a retry capability.

原文: https://angular-2-training-book.rangle.io/handout/observables/observables_vs_promises.html