FirefoxDriver : Firefox driver is included with selenium-server-stanalone.jar. It comes in the form of firefox extension (xpi). It is added to the firefox profile when user start a new instance of FirefoxDriver.
InternetExplorerDriver : InternetExplorerDriver supports 32-bit and 64-bit browser versions. The InternetExplorerDriver is also part of standalone server.InternetExplorerDriver implemented with WebDriver's wire protocol.
ChromeDriver : ChromeDriver is available for Chrome Android and Desktop.
Other popular drivers used for Selenium are as follow: