It’s been quite a while since Chevrolet and GMC trucks have had identical names.
Both Chevrolet and GMC full-size pickups used to simply be referred to as the C/K. C1500, C2500, and C3500s were two-wheel drive; K1500, K2500, and K3500s were four-wheel drive.
----Since their 1999 redesign, the full-size Chevrolet pickup is called Silverado, and the GMC version is Sierra.
For the mini pickups that came out in 1984?, Chevy’s was always the S-10, GMC’s the S15. I think the GMC one is now called Sonoma.
The big two-door SUV was the Chevy C/K Blazer, or the GMC Jimmy. Neither is made anymore, but the GMC one was renamed the Yukon before being phased out.
The mini-SUV was the Chevrolet S-10 Blazer, and the GMC S-15 Jimmy. After the full-size units were discontinued, they started simply calling them Blazer and Jimmy.
I think it was 1995 when they came out with the Chevy Tahoe, and GMC Yukon 4-door, which are slightly shortened Suburbans.
For years, the Suburban was made as both a Chevrolet or GMC. Now, GMC’s version is the Yukon XL.
Incidentally, GMC appears to be marketed as the more luxurious brand of the two. The Yukon Denali, Yukon XL Denali, and Sierra Denali have a lot of equipment you don’t see on the Chevrolets. Also, the GMC Envoy has optional woodgrain dashboard accents, and the Chevrolet Trailblazer does not.