Shows your recent messages at the top of your inbox. Default inbox type set, tried and true.
Gmail analyzes incoming messages based on your past interaction for similar messages and gives top spot for those you interact with most and other important messages.
Shows on top all those messages you haven’t read yet so that you easily can get a glace of what’s new @inbox and read them first.
Shows only those email messages that you’ve starred at the top of your inbox.
Using priority inbox you can combine unread, important and starred inboxes and let everything else show separately. You can customize your priority inbox type and set inbox sections that suits you best in your inbox settings