A GridView displays your data source in an HTML table and extends it to allow paging, sorting, editing etc. A repeater is a template control, where you specify the html that is used to render each row. A gridview can only show your data in a table, but a repeater can show your data in any way you want by creating the relevant ItemTemplate. For example you might show a list of products, with each product having an image, description, list of colours, price etc, all arranged as you'd normal see a product listing. A repeater can supply that kind of display flexibility.

http://24x7aspnet.blogspot.in/2009/06/feature-difference-between.html