An Imaging pulse is very thin front to back so it is not on a subject very long.
A 2D pulse is a somewhat inverted cone shape and will detect anything within its coverage for a lot longer period of time. More time=more pixels lit up=more history recorded.
The spec coverage angle for 200 kHz is 20 degrees. That equals 1/3 the depth.
The spec coverage angle for 83 kHz is 60 degrees. That equals the depth.
The Imaging pulse is just a few inches from front to back.
If you want more pixels lit with Imaging, increase your Chart Speed and stuff will take up more screen space.
This is a large brush/log pile with the three technologies:
With Imaging, the size of the parts of a brush pile is what is recorded, not an exaggerated blob like 2D does.