Sport+ will also change the gear switch positions so that the engine is always revved above 2-3k rpm in auto mode. This is slightly higher than sport mode with 2-2.5k rpm. Try it, when in the highway at a constant speed, switch to sport and then sport+ you will see the difference.
I also feel it will hold on to gears for longer after accelerating. I've seen it keep my engine at 4k rpm after releasing the pedal.
Just my 2 cents after running around in the two modes for a bit