Think about it this way:
Pacer - club rider, backpack commuter, gravel racer. The Pacer does not have as many braze-ons for mounting racks and bags as the others, plus the geometry is not designed with fully-loaded touring in mind, so while it will handle long distances well with lower weight cargo, heavier loads will affect it's handling and your heels are more likely to hit rear panniers on this model.
Cross Check - light duty tourer, pannier commuter, and versatility for practically any build you dream up. Versatile as all get out, but somewhere between touring and "road" geometry.
Long Haul Trucker- cross country tourer, heavy duty commuter, practically begs you to bring the kitchen sink. All the bells and whistles. Low BB and long stays make it good for racks and bags but not as good for technical off-road trails.
Sure, there's a lot of cross-over between them in what they CAN do - they all make excellent commuters for example. They simply excel a bit more in one area or the other than the next.