need info about winners

Question

hello, i want to know the winners of forums and winners who post new articles blogs etc are diffrent??

how they decide about winner of months? based of their contribution in current month for articles and etc or based on their ans marked for post in forum

here march month winners are differend:

http://www.c-sharpcorner.com/News/NewsDetail.aspx?NewsID=587

and when i click on and select 2010 march their it shows different winnsers:

http://www.c-sharpcorner.com/Forums/Members/Winners.aspx 

please give some info.