Electric Fan pin 33 and 42

[bh2fan]

Hello,
Trying to do an electric fan conversion on an 05. I have read that there are two output pins (pin 33 and 42) that can be enabled to control two electric fans.
From what I have read, most people use pin 42 only, why? Can anyone explain the functions of pin 33 and 42? Does only one pin turn on the fan when A/C is on? Does the PCM turn off the fans when a certain vehicle speed is reached?
I know that 94-96 B-body vehicles have two pins and fan 1 turns on when temperature is 225F and or A/C head pressure is above 189psi. Fan 2 turns on when temperature is 232F and A/C 240psi. Both fans do not come on when vehicle speed is above 45 mph or so. Is it something similar for the H2? Thank you.