Big difference in size. Those numbers may look short on paper but the are big. Especially the width. Way more room in the cab of the Silverado.
I love this truck more than my Camaro guys, seriously. I traded a 2011 Silverado on the Colorado, no stranger to half tons and they have solved every niggly issue I had with my 2011.
Spray in bed liner! Yay, no more stuff sliding around on the slippery assed drop in box liner.
That headlamp, 4x4 and trailer brake controller are all on the left side, up by the vent instead of at the bottom of the dash by your left knee, yay!
Universal home remote and integrated trailer brake controller are not even offered in the Colorado. I wtf'ed at that when I bought it.
Power folding mirrors are nice for parking in my garage and drive through windows

The nav/infotainment system is leap years better than my 2011, identical to the Colorado's though.
Bose stereo sounds great, better than the Bose in my 2011.
The saddle leather interior on the high country edition is jaw dropping gorgeous. Cooled seats yay! I am sick and tired of black leather interiors.
Instrument cluster is killer looking, color lcd is very nice too.
Forward and reverse parking sensors as well as collision alert and lane departure alert.
The dish in the armrest is an induction charger for your smart phone, yay! No more plugging in.
This thing drives very nice, quiet and smooth, they managed to put a bit of growl into the exhaust when you get into it though, something the 2011 5.3's did not have.
I can drive around in 4wd and not even notice the front hubs are locked in. Colorado would barely turn a corner in 4wd.
Anyhoo, the Colorado was the most unrefined vehicle I've owned since my 1978 Mercury Monarch beater wagon. My 1991 Buick century beater wagon was nicer to drive than the Colorado, sheesh. GM missed the boat in my opinion. Wound up hating driving it.
I was 3k upside down on my lease but the dealer ate it and paid it out in full. My Silverado is a 2015, got it for $7500 off sticker and 0% financing.
Insurance on the Silverado is only $5 more a month.
The sunroof on my 2011 has a mesh screen slider that still let a ton of light in when closed, the 2015 has a solid cloth slider, yay.