About Subdivision
Subdivision is a method of refining the control mesh and making the surfaces smoother. In subdivision, new vertices are added to create a more complex and finer mesh.
On the Freestyle tab, select one or more shapes from the Freestyle Tree or graphics window and click 
Subdivide.
Subdivide.Differences Between Subdivision and Resolution
In Subdivision, you subdivide the shape for a finer and complex control mesh. In Resolution mode, the control mesh does not change. However, when you apply the resolution level, new vertices are created, and a virtual control mesh appears. If you exit Resolution mode without resetting changes made in Resolution mode, the following occurs:
• You can manipulate the mesh by using the commands on the Manipulate group on the Freestyle tab.
• If you click other commands from groups such as Associate, Create, or Symmetry on the Freestyle tab, an error message appears stating that performing this operation may remove the mesh changes made in Resolution mode.
Therefore, you can transform or scale the virtual control mesh created in Resolution mode without losing changes made in Resolution mode. If you do perform an operation that results in the addition of new vertices, then you might lose changes made in Resolution mode.