Yeah, those were some of the things I've noticed. Honestly, when I built both the Colorado and Canyon, I put the same options in and the Canyon always came out a little more expensive every time. From first glance, I wouldn't be able to tell the difference of the interior quality, but they've got to put something else these trucks for them to be more expensive than their Chevy counterparts!
Not really . . . mainly marketing angles that's all.
Being that they are built at the same plant with the same engines and most other parts it does come down to preference. To us, the GMC always had the more squared off real truck like styling cues in area like fenders, grille and other lines. The Colorado design seems more SUV-like with a more flowing design with curves and a more elegant appearance. So the Colorado can be equipped also with more upscale and functional features. Even the GMC Denali only has maybe 3 or 4 items than a well equipped Colorado LT (ie, cooled seats, heated steering wheel, phone charge pad, etc)
In the end, it all is a preference and your tastes and money !
Also, often overlooked is you can get the Luxury and Convenience Packages in the Colorado LT which takes it up another notch with more upscale things and a two tone Dark Ash/Black seating and interior leather option. . .
LT Convenience Package
(C49) rear window defogger,
(A2} rear-sliding window,
(T3U) front fog lamps,
(BTV) Remote vehicle starter system,
(PPA) EZ-Lift tailgate and
(DG6) outside heated power-adjustable,
body-color, manual-folding mirrors.
Luxury Package Chrome
(AAQ) 4-way power front passenger
(AL9) power driver lumbar control,
(AT9) power front passenger lumbar control,
(KA1) heated driver and front passenger
(C68}single-zone automatic climate control,
(T3C) projector-type headlamps,
(DD} inside rearview auto-dimming mirror,
(DL9) outside heated, power-adjustable,
manual-folding Chrome mirrors,
(VJH) Chrome rear bumper and
(E20) Chrome door handles
Also Includes required H2U or H2V Leather Seats.