Got my copies today. I've not watched the DVDs yet, but there are big differences.
Cardio circuit has a total of 30 different exercises! 23 in the main program 7 in the cooldown.
Ropes & Straps has 16. 9 in the main program, 7 in the cooldown. It is done in a pyramid style, where you work up to the hardest, then repeat the exercises in reverse.
The exercises in Ropes & Straps look more demanding of strength, but with a little less of a cardio focus.