High School Physics, applied.
http://en.wikipedia.org/wiki/Lever
ClassicalMechanics.. It is about Leverage, Mechanical Advantage..
Fulcrum/pivot relationship to where the effort is applied and the work being done.
a V brake caliper has high MA, significantly more cable pull to pad moving towards the rim (a ratio)
in order to supply enough cable pull the hand lever must have a low MA
and pull more length of cable.
cantilevers brake levers need to pull less cable, the hand lever has the higher MA
the caliper a lower MA.
also Note: there are 2 types of levers used in cantilever brake calipers.
only type one 1, where pivot is between cable pulling and brake pad,
is the high profile L shaped type..
compact/low profile and V brakes the pivot is the . so is a type 2 laver.
in short, you should be able to judge the MA of the lever in your hand,
by applying some ancient science, as you squeeze the lever.