Great, I was hoping the picture showing the two choices would be posted.

The top item is the smart switch box that contains the switches AND the Auxiliary Input Module circuitry that is needed to work with an Ag Leader system where switches are required.

The bottom item is the Auxiliary Input Module which communicates with the system but does not contain any switches. Separate external switches are needed. These other switches could be the original switches that came with a sprayer, a single hand toggle switch, a single foot toggle switch, an Ag Leader dumb 10 boom switch box or even a homemade one like I mentioned above.

Either is functionally equivalent.  The decision to use one or the other is often related to the situation such as need for switches and cab clutter. 

You may be curious as to why the smart switch box has the brown and gray connectors besides the CAN connector These are for other possible switches and/or a speed connector to go to an external radar gun. For example with a hydraulic drive module on a planter an external momentary jump switch is connected to the brown connector. In many cases, such as my planter tractor, those connectors are not used.