For users of WebDriver API’s, this is a drop-in replacement. The major change being, removing the core and replacing it with the back-end WebDriver. Selenium 3.0 has become a W3C (world wide web consortium) standard. Also, Selenium 3 would be majorly looking to be a choice of software testing tool for both web and mobile-based applications.
Let's understand to compile the entire list of features which separate the two −
|Selenium 2||Selenium 3|
|Selenium 2 is the combination of WebdDriver+SeleniumRC (Selenium1) which is based on selenium core.||The core is removed from Selenium3 but supports Selenium RC indirectly through back-end Webdriver.|
|WebDriver contributes its object-oriented API for Document Object Model (DOM) interaction and browser control. Firefox is the default browser.||Browser vendors will ship their own WebDriver implementation, hence are tightly coupled to the browser giving a better testing experience.|
|Supports both the Selenium RC API, and the Selenium RC technology underneath the WebDriver API.||No Web Driver API. GeckoDriver has been introduced for Firefox (v47 and above) regardless of any version of Selenium.|
|Mozilla, Chrome, IE implant their driver which is developed by Selenium developers.||Modern Browsers such as Edge, Safari are introduced with the WebDrivers shipped by their vendors|
|Use of AndroidDriver and iPhone driver for mobile Automation.||Use tools such as Appium for Mobile Automation.|