Difference between 公告 and 通知? 通知 and 公告 both mean a notification from the authority.

But any difference? Could somebody help me figure out the difference with some concrete examples?
公告


  announcement, public announcement, proclamation, public notice


通知


  notice, inform, notify


A 公告 is a 通知 to the public.

A 通知 can be private or public. 

公告 =  通知 + publicity