No input is allowed, so use only for prompts. A Text box does the same, but can receive input, so is useful for responses to questions. A Check box is a toggle switch. An Option button is used to select an option, but these are usually used in sets, to select one from a set of mutually exclusive options. List boxes display a list of items, from which the user will normally select one.
Scroll bars are self-explanatory.
The Timer is used to time an event or control events which are set to take place at set intervals. The timer is not displayed once the program starts running. Drive boxes, Directory List boxes and File List boxes are all used for file management dialogues, usually these are all used together. A Shape and a Line can be drawn for various effects on the form. These offer limited graphics.