Many make a blind choice of choosing data grid directly, but that is not the right way.

Data grid provides ability to allow the end-user to sort, page, and edit its data. However, it comes at a cost of speed. Second, the display format is simple that is in row and columns. Real life scenarios can be more demanding that

With its templates, the Data List provides more control over the look and feel of the displayed data than the Data Grid. It offers better performance than data grid

Repeater control allows for complete and total control. With the Repeater, the only HTML emitted are the values of the data binding statements in the templates along with the HTML markup specified in the templates—no "extra" HTML is emitted, as with the Data Grid and Data List. By requiring the developer to specify the complete generated HTML markup, the Repeater often requires the longest development time. However, repeater does not provide editing features like data grid so everything has to be coded by programmer. However, the Repeater does boast the best performance of the three data Web controls. Repeater is fastest followed by Datalist and finally data grid.

See the following .NET interview questions video on difference between Constant and Readonly: -