While most of the unique characteristics associated with micromachining with ultrafast lasers can be explained by the lack of thermal diffusion, some important features, notably the extreme high shot-to-shot repeatability, the ability to create sub-micron features, and the capability to machine inside transparent materials, requires a more detailed look at the physics behind the interaction of light with matter.
How does light interact with matter? The following links will help us get a deeper understanding.
Positioning of the laser beam with respect to the work piece
Stochastic or deterministic nature of the ablation process