The ListBox and ComboBox controls are two of the most common list controls used in Windows applications. They can be used to allow the user to enter data by selecting an item from a list. The ListBox allows both single-selection and multiple-selection, while the ComboBox allows you to type text if you don't find the selection you desire in the list.
The ComboBox control also has a DropDownStyle property that allows the control to be used in one of three modes:
DropDown (the default) displays a textbox-like control with an arrow next to it that can be used to drop down the list. An item can be selected from the list or typed into the textbox-like control.
Simple displays a textbox-like control with a list ...