In the field of polymers, 2D images are often used to discern information about the microstructure of bulk polymer materials. For brush particle assembly structures, this work evaluates microstructure information retrieved from different material characterization techniques for thin film (i.e., electron imaging of brush particle monolayers) and bulk materials (small angle X-ray scattering), respectively. The effect of confinement of polymer chains into thin (2D) films on the conformation of tethered chains is discussed and used to rationalize systematic discrepancies between characteristic nanoparticle spacings in thin films and bulk materials. An approach to rationalize bulk material properties based on thin film measurements is presented.