What's the difference between 90's Chevy trucks and 90's GMC trucks?

GM liked badge engineering. They profited from it big time. Pontiac's, Buick's, Oldsmobiles, Chevrolets, Saturns, and Cadillac's all copied each other. But the most obvious was GMC and Chevy. There is no difference between the two except for brand name. It is true that today there is a larger difference between the two. The GMC Sierra and Chevy Silverado are still twins. And the GMC Canyon and Chevy Colorado are still twins. And the TrailBlazer and Envoy. And the Chevy Tahoe/GMC Yukon. Every GMC is a copy of a Chevy. But the following GMC's at least look like different cars. The Acadia and Traverse, and the Equinox/GMC Terrain.

the gmc sierra is exactly the same as the chevrolet silverado as far as I can tell the gmc canyon is the same as the chevrolet colorado as far as I can tell. The gmc yukon is the same thing as the chevrolet tahoe as far as I can tell. They are the same prices and everything. I think GM could shut down GMC, or phase out chevy trucks, because as far as I can tell, they are still twins