Straight from the Microsoft Help:
The Refresh method immediately updates the records in the underlying recordsource for a specified form or datasheet to reflect changes made to the data by you and other users in a multi-user environment.
The Requery method updates the data underlying a specified form, or a control that's on the active form, by requerying the source of data for the form or control.
The Repaint method completes any pending screen updates for a specified form. When performed on a form, the Repaint method also completes any pending calculations of the form's controls.