The featured image (also known as the "post thumbnail") is the primary image associated with a page, post, etc., which shows up in various areas of the theme. Use with the [wordpress] tag.
Dynamic Featured Image dynamically adds multiple featured image (post thumbnail) functionality to posts, pages and custom post types. It enables the option to have MULTIPLE featured images within a post or page. This is especially helpful when you use other plugins, post thumbnails or sliders that use featured images. Why limit yourself to only one featured image if you can do some awesome stuffs with multiple featured image? DFI allows you to add different number of featured images to each post and page that can be collected by the various theme functions.
(From Wiki)
