From Selenium perspective, the WebDriver Interface is similar like a agreement which the 3rd party Browser Vendors like Mozilla, Chrome, Internet Explorer, Safari, etc have to adhere and implement the same. This would in-turn help the end-users to use the exposed APIs to write a common code and implement the functionalities across all the available Browsers without any change.

Through WebDriver driver = new FirefoxDriver(); we are creating an instance of the WebDriver interface and casting it to FirefoxDriver Class. All the Browser Drivers like FirefoxDriver, ChromeDriver, InternetExplorerDriver, PhantomJSDriver, SafariDriver etc implemented the WebDriver interface (actually the RemoteWebDriver class implements WebDriver Interface and the Browser Drivers extends RemoteWebDriver). So if we use WebDriver driver, then we can use the already initialized driver (as common object variable) for all browsers we want to automate e.g. Mozilla, Chrome, InternetExplorer, PhantomJS, Safari.

A WebElement is an abstraction used to identify the Element nodes and are simply known as elements when it is transported via the protocol, between remote and local ends. The web element identifier is the string constant expressed as:

From Selenium's perspective, the What is the difference between ChromeDriver and WebDriver in selenium? interface is similar like a agreement which the 3rd party Browser Vendors like Mozilla, Chrome, Internet Explorer, Safari, etc have to adhere and implement the same. This would in-turn help the end-users to use the exposed APIs to write a common code and implement the functionalities across all the available browsers without any change.

Through the line of code:

WebDriver driver = new FirefoxDriver(); 

We are creating an instance of the WebDriver Interface and casting it to FirefoxDriver class. All the Browser Drivers like FirefoxDriver, ChromeDriver, InternetExplorerDriver, PhantomJSDriver, SafariDriver etc implemented the WebDriver interface (actually the RemoteWebDriver class implements WebDriver Interface and the browser drivers extends RemoteWebDriver). So if we use WebDriver driver, then we can use the already initialized driver instance (as common object variable) for all browsers we want to automate e.g. Mozilla, Chrome, InternetExplorer, PhantomJS, Safari.

A WebElement is an abstraction used to identify the Element nodes and are simply known as elements when it is transported via the protocol, between remote and local ends. The web element identifier is the string constant expressed as:

Why WebDriver driver = new FirefoxDriver();

Through WebDriver driver = new ChromeDriver(); we are creating an instance of the WebDriver interface and casting it to ChromeDriver Class. All the Browser Drivers like FirefoxDriver, ChromeDriver, InternetExplorerDriver, PhantomJSDriver, SafariDriver etc implemented the WebDriver interface (actually the RemoteWebDriver class implements WebDriver Interface and the Browser Drivers extends RemoteWebDriver). So if we use WebDriver driver, then we can use the already initialized driver (as common object variable) for all browsers we want to automate e.g. Mozilla, Chrome, InternetExplorer, PhantomJS, Safari.

From Selenium perspective, WebElement represents an HTML element. Generally, all the operations to do with interacting with a page will be performed through this interface.

Each browsing context has an associated list of known elements. When the browsing context is discarded, the list of known elements is discarded along with it.

Some of the commonly used associated methods are as folllows:

WebDriver driver = new FirefoxDriver();

Through WebDriver driver = new FirefoxDriver(); we are creating an instance of the WebDriver interface and casting it to FirefoxDriver Class. All the Browser Drivers like FirefoxDriver, ChromeDriver, InternetExplorerDriver, PhantomJSDriver, SafariDriver etc implemented the WebDriver interface (actually the RemoteWebDriver class implements WebDriver Interface and the Browser Drivers extends RemoteWebDriver). So if we use WebDriver driver, then we can use the already initialized driver (as common object variable) for all browsers we want to automate e.g. Mozilla, Chrome, InternetExplorer, PhantomJS, Safari.

From Selenium perspective, WebElement represents an HTML element. Generally, all the operations to do with interacting with a page will be performed through this interface.

You can find a detailed discussion in Values returned by webdrivers

Each browsing context has an associated list of known elements. When the browsing context is discarded, the list of known elements is discarded along with it.

You can find a detailed discussion in Why return type of findElement(By by) is WebElement?

Some of the commonly used associated methods are as follows: