I can help you with the sound car, but I don't know much about the sensor boxcar.
According to the description these are not command controlled at all. There is a sensor near the wheel that determines speed / movement and the boxcar plays all kinds of freight sounds based on that movement (they are very realistic in my opinion and sound really cool)
The Vision Reefers add a lot of triggered dialogue that can go on for minutes to hours depending on how long you want it to go, it also adds loading and unloading as well as brake sounds.
Hope that helps!
