Of course, this is just my opinion, and a ton of older vehicles that are considered cars would fall into this category. Heck, a standard Jeep Wrangler would fall into this category.
Furthermore, there isn't any reason you couldn't make a truck (that is, a pickup) using a unibody approach, but I don't know of any examples (which just may be my ignorance).
Regardless - I always consider anything modern with a ladder frame to be a "truck". It may not be a pickup, but to me it's still a truck.
That hilariously restrictive definition would have classified my old beast of an ex-military cargo vehicle as a "minivan", but I doubt you'd convince any onlooker to label a vehicle like this as anything other than a "truck":
Yeah - technically. But this whole discussion is about the consumer space, not about those purchasing commercial equipment for hauling tonnage or whatnot.
Even so, though - there are plenty of consumer pickup models which are used commercially, and more than a few can handle some pretty big loads (especially towing)...
GVM > 4.5 ton is what makes a truck. Anything less is not a truck. 4.5 to 8 ton is light, 8 - 12 is medium, 12 ton an up is heavy for rigid trucks. That thing is a SUV.