Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that. Boring web-based administration tasks can (and should!) also be automated as well.
Cypress is a front end automated testing application created for the modern web. Cypress is built on a new architecture and runs in the same run-loop as the application being tested. As a result Cypress provides better, faster, and more reliable testing for anything that runs in a browser. Cypress works on any front-end framework or website.
Protractor is an end-to-end test framework for Angular and AngularJS applications. Protractor runs tests against your application running in a real browser, interacting with it as a user would.
It brings together the power of WebDriver, the elegance of jQuery content selection, the robustness of Page Object modelling and the expressiveness of the Groovy language.It can be used for scripting
It is a testing framework designed to simplify a broad range of testing needs, it covers all categories of tests: unit, functional, end-to-end, integration, etc.Run your tests in arbitrarily big thread pools with various policies available (all methods in their own thread, one thread per test class, etc.