How are rich media ads different from other ad formats?
They are displayed on the Search Network
They are a type of text ad
They are static image ads
They are ads with animation or other types of motion
Rich media ads allow you to more actively engage a web user than standard text or display formats. Rich media ads include video ads, Flash animated ads, and ads that mix text and animated content and designs. You can easily create these types of ads using the AdWords Ad gallery, or you can use existing rich media assets served through a third party ad server.
Read more here: https://support.google.com/partners/answer/172610