any difference in sport mode?

The steering definitely feels tighter to me in sport mode. Ride is stiffer too as others have noted. It should also change shift points--and it does seem to shift more affirmatively, but it is subtle.

I can definitely feel it on my 2.0T. The shifting is faster, the throttle is more aggressive (good to scoot off the line in traffic), and the steering is firmer.

Other than the ride you do need to drive a little more aggressively to show the difference, and the steering is more noticeable at speed. Just driving in the city in traffic it isn't much different. The exhaust sound inside is a little louder also. In track mode there is a pretty big change in everything.

Cadillac has some intelligence built in where it looks for "spirited" driving.

You can really tell when you pass that threshold in Track mode in the Vsport.

I have a 2.0T lux with no MRC (I long terribly for it).

So while my ride doesn't change of course since I don't have an adjustable suspension, its only steering and shifting. My steering definitely weights up immediately from tour mode. As for the transmission, per the manual it has what is called "performance shift" which is only activated when you begin driving more aggressively in sport mode. I've only noticed it in heavy throttle applications as it will hold gears longer especially if you go full or heavy part throttle and then let off.

Some one said that if you have AWD, in sport mode it is RWD only. Never able to confirm this.