Selenium RC has a complex architecture whereas in WebDriver those complications are removed. Let us discuss why WebDriver is better than the RC.

Selenium RC is slow because it uses an additional JAVASCRIPT LAYER known as the core and On the other hand, WebDriver is fast as it natively SPEAKS with the browser by UTILIZING browser's built-in engine to control it.

The selenium core can not ignore the disabled elements while WebDriver handles the PAGE elements more realistic way.

Selenium RC has a more mature set of APIs but contains redundancies and complicated and confusing commands. Whereas, WebDriver APIs his simpler and have a cleaner interface and do not have redundant and confusing commands.

Selenium RC does not provide support headless HtmlUnit browser. It requires a real visible browser to operate on. On the other hand, WebDriver supports a headless HtmlUnit browser.

Selenium RC includes a test result generator for HTML reports. Whereas WebDriver does not have any built-in reporting ability.