When you increase muscle mass you will also boost your metabolism and that of course will burn more calories. According to the National Strength and Conditioning Association this is because a pound of muscle can burn up to three times as many calories as a pound of fat! This is why you want to include some weight training program right along with some cardio exercise. And it only requires two days a week. This can include bicep curls, push-ups, and squats. If time is limited include more of the larger muscles because those larger muscles will burn more calories!
Cardio exercise is still important for your heart and it also helps your metabolism in a different way. It supports losing fat mass and increases your resting metabolism for a few hours after the activity! So yes, you are even burning more calories when you are sitting there watching TV if you've invested in an adequate cardio workout previously.
So the answer to the question of what burns more calories, is both kinds of exercise. When you have lean muscle from weight lifting it continually burns more calories at rest. Cardio activity burns calories immediately and for a few hours afterwards.
Do cardio, at least 5-6 times a week for 30-40 minutes and then include some weight bearing exercise twice a week. Then you will have the best metabolism and get even more of a good calorie burning boost.
Just don't forget what you eat is more responsible for your weight loss success than anything else, in fact over 80-90% of your success! So follow your diet plan if you are a CMWM patient, and make sure you cut out any junk food, give up soda, (even diet soda) and always eat REAL UNPROCESSED FOODS: veggies, fruits, and lean protein.