From what I know, being overweight means you can both build muscle and lose weight at the same time, at least initially. Probably because weight training as your form of exercise is a) going to make you stronger and b) going to make you lose weight, simply because it's excercise.
However, this doesn't last forever, you'll hit a plateau, and at a point you will need to decide - do you want to continue to build muscle (gain weight again/bulk) or to lose weight (referred to as a cut). Many professionals cycle between these, building muscle in a bulk, and then showing it all off (but losing some) in a cut. I'm guessing you knew that part though.
Then again, don't cheat yourself out of cardio. Your lungs and heart will thank you for that one lol
Either way, best of luck to you on your journey!