Now resistance training of any form (bands, cables, weights, calisthenics) is said to burn up to 2 times the amount of calories as just regular steady state cardio. Now this can be true, but it's not going to be true if you're taking your sweet time in between sets, not using enough weight, not doing enough reps, and most importantly not pushing yourself to your limits. In that case the person doing cardio on the treadmill lets say will be burning more calories than you. As for cardio though you can easily burn 100's of calories in short amount of time, but you're not going to do it walking 3.5 mph with a 4 incline, if you're going to do that you're wasting your time in my opinion. In order to burn a ton of calories doing cardio you need to do HIIT, or high intensity interval training, which calls for short bursts of very high intensity actions followed by a longer rest period and then repeated over and over again. For example you walk on the treadmill at 3.5mph for 2 minutes, then once the 2 minutes is up you bump up the speed to as fast as you can go 8, 9, 10 mph for only 30 seconds. Once the 30 seconds is up drop it back down to a 3.5mph speed for another 2 min and repeat! HIIT is one of the best things for burning calories, and getting you in shape fast!
Both resistance training cardio have their unique benefits, but as for which one is better for getting skinnier, that's all dependent on you and how hard you push yourself! You should try and incorporate both types of training into your regimen though!