jasmine and mocha are test frameworks (they're the things that supply your describe() and it() functions), but they don't really supply you with everything you need to get set up to run tests.

jest is a test runner that includes a few additional things to try to make all aspects of writing and running tests a little easier...such as:

* Searches for tests to find + execute so that you can put tests near the modules they are testing

* Runs tests in parallel processes so that your test runs finish sooner

* Replace's node's built-in require() function with a custom one that acts almost entirely the same -- except (by default) it returns mocked versions of modules (rather than the real things) when your tests run

* Gives you a fake DOM implementation (using jsdom) so that you can test code that depends on DOM APIs on the command line without having to boot up a browser