"NPSR" (Narrow Profile Supply Reels) are are "tall and narrow" and taller than most reels found elsewhere. As a result, they hold more hose than similar reels, for a given width. And their width can be adjusted for more- or less- capacity on an as- needed basis.
"LPSR" (Low Profile Supply Reels) are low and wide. Designed to be mounted on the floor or at the ceiling, in front of your vacuum reel- in line with it (not off to the side), they offer you the narrowest possible footprint in your van or truck, so they give you the widest floor space possible.