Confused between MobileElement and AppiumDriver class which contains different swipe methods

Hi,

I need to know what is the difference between Mobile Element and AppiumDriver. I know MobileElement is subclass of WebElement and other one is subclass of RemoteDriver, is there any other thing?

But i got confused when i see swipe() method is present in both the class with different parameters.

Q: Why there are two swipe in different class?
Q: When to use which swipe, how to decide ?

Refer:
http://appium.github.io/java-client/io/appium/java_client/MobileElement.html
http://appium.github.io/java-client/io/appium/java_client/AppiumDriver.html

Regards
Sheetal