The difference was seen by sifting the resin heads with different sizes screens. The difference is only about 25 microns. For reference, a human hair averages 100 microns in thickness.
"Large" in this example would be 120 microns, "small" would be 90-73 microns. The difference is small, but consider the volume of a sphere increases with the radius cubed. So the 120 micron trichome has a volume almost 1000 x greater than the volume of a 90 micron trichome.
This only really matters if you're making extracts IMO.