RetiredMil wrote on Mar 15^th, 2019 at 2:04am:

. . . When you talk about a reduced load are you talking about (A) the case not being filled to the bullet or (B) just less powder reducing the pressure and rate of travel?

(A) is reduced "loading density" or "fill ratio".

(B) is "reduced load" - which can be anything from pipsqueak "cat sneeze" gallery rounds to loads just palpably below "maximum". Depending on powder bulk density and burning rate, reduced loads can sometimes fill the case, but most exhibit reduced load density. Confused yet?