You should try to consult the wiki
from time to time.
[quote:26m41f7y] Application runtime
The Application runtime does not have the DirectX display engine, hence you cannot show any DirectX graphics (sprites, tiled backgrounds, etc), but it also means there is no requirement to have any version of DirectX installed at all for it to run. The main purpose of this runtime is for application development using windows controls (buttons, comboboxes, dialogs, and such).
This runtime also has a smaller filesize and is quicker to load.