Selenium 1 VS Selenium 2

Summary	Detail
Selenium 1	2004 when Jason Huggins He developed a Javascript library that could drive interactions with the page, allowing him to automatically rerun tests against multiple browsers. Selenium RC was ground-breaking because no other product allowed you to control a browser from a language of your choice. It ‘injected’ javascript functions into the browser when the browser was loaded and then used its javascript to drive the AUT within the browser. Selenium-RC worked the same way for each supported browser. It ‘injected’ javascript functions into the browser when the browser was loaded and then used its javascript to drive the AUT within the browser
Selenium 2	In 2006, Google named Simon Stewart started work on a project he called WebDriver It drives the browser directly using the browser’s built in support for automation. Selenium-WebDriver makes direct calls to the browser using each browser’s native support for automation. How these direct calls are made, and the features they support depends on the browser you are using.