Subdivide, Subdivide Selected
Subdivides the entire object regardless of current sub-object mode. See the image below for a simple example. Typically you will do this to add additional detail to your model.
Subdivides only the selected faces. See the example below where we have subdivided a single face. You may or may not want to fix resulting 5 sided polygons.
Created with the Personal Edition of HelpNDoc: Create iPhone web-based documentation