Again there's no difference, but I'll try and be a little more thorough in my answer.
Both 12V and 24V solenoids will run off on an NI-9472 module (or more commonly known as a solenoid module). You will plug your solenoid (regardless of its voltage) into the module with the
breakout installed. You will code both types of solenoids the exact same way - open them, and control weather or not each port on the breakout is an open or closed circuit.
Now, here's the only difference: the solenoid breakout requires a power input (it's on the top left of the picture on the linked page). It can handle
both 12V and 24V (but not at the same time). You will either wire 12V or 24V from your PDB to that breakout. Note that you can not use both 12V and 24V solenoids simultaneously on the same cRIO module.
So, really, there is not any difference between the two voltages of solenoids, except the power your wire to them.