school me on dry sump oil pumps

[93superHICAS]

ok ive been doing some research about dry sump oil systems for quite a few months now, off and on here and there.
today i was looking into the dry sump oil pumps and they had different stages.
stages 1-6.
so school me on why and what are the differences from different stages.
is it just the ports on the pump that feed different things on the motor. like oil filter, oil cooler, etc etc?
ive did a quick search and couldnt find any information on why they have these different stages.
and how many ports (in/outs) would i need.?

thanks in advanced