You know hotter weather = less dense air, therefore less power at same boost.
I'll give an extremely basic overview of the difference...
Boost tune will run 18psi all day long, whatever the weather... In summer you'll get 400NM, winter 450NM
Load tune will target (for example) 420NM all year long, and alter boost from 19psi to 17 psi as needed.
A hybrid tune will do a bit of both, if you hit either 18psi or 420NM the car will stop increasing boost
From what I have seen, most "hybrid" tunes are a boost tune with load caps in place to stop excessive torque production during colder months
Resident tuner @
richierichness might be able to shed some more light on the matter