WP as tumblr

I have seen that some themes turns WP to act like Tumblr. I am talking mostly about the styling, when you write a quote it has different layout, when you post an image a different style etc.

How is that supported? Is something that theme supports or it is a native WP feature? How it separates categories “quote, video, photo, etc..” ? Is it a a custom field or what?

Please explain a few things about it.

Thanks