That said, a lot of those variables are set into the program and a Correction method used to make different types of dynos, temps, diff ratios, pressures, etc read "the same" as each other.
Never works out that way though.
In the end of the day: If you want to compare one car to another, you put them next to each other on a track or drag strip.
If you want to compare your car to a previous tune, you do it on the same dyno and look at the graph/numbers.
I learnt real quick that numbers mean nothing, especially peak power figures. If you've got no midrange, or torque, you're going to get raped by that bodykitted excel golf with frangipani stickers teh lowz.