Question [Q] What is the function for Running button in Tab App Drawer

Hello,

I'm using i9100G, and there are 3 tab button in App drawer which :

> ALL
> RECENT
> RUNNING

I'm wondering why too many application in Running, some of them I'm not even used. I tried kill the app but sec later, the app restart to running.

And what is the different between running program in app drawer with the one behind task manager?