What is the difference between the exercise made to bulk up and the one to slim down?

I don’t get how that works. Some exercise to lose weight, and others to bulk up. What is the difference between those exercises? Or is it really what you eat that makes the difference?
I’m currently trying to bulk up in the legs and butt, and slim down in the waist and abs area. How can i make sure that my legs don’t get thinner because of the workout, and that my muscles around my abs and waist don’t get bigger?

WINSOR PILATES 2 DVD SET + RESISTANCE BAND + COOKBOOK. SCULPT YOUR BODY SLIM FASTER!

• Mari Winsor is one of the most sought-after trainers by the biggest stars and celebrities in Hollywood.
• DVD 1: Winsor Pilates Back Workout (20 minutes) is for women and men who want to build a stronger, more flexible back. This workout focuses exclusively on your back. Mari Winsor designed The Back Workout so that in 20 minutes you will: (1) Increases flexibility and loosen up the tight areas of your back. (2) Develop muscle strength so that you feel balanced and in control. (3) Tone your back muscles so you look good and feel good. (4) Achieve better posture.
• DVD 2: Power Sculpting with Resistance DVD (28 minutes) – A studio-type Pilates workout right in your own home! Power Sculpting With Resistance delivers a Pilates Studio workout without the expensive equipment. By combining the benefits of resistance exercise and Pilates, it can sculpt and transform your body even faster than you thought possible. Maris exclusive Dynamic Sequencing Technique helps you strengthen, firm and tone your muscles. Its also great for when you are pressed for time.
• RESISTANCE BAND (6 feet long, blue color) – a stretchy Sculpting Band that adds even more effectiveness to Mari Winsors usual dynamic sequencing Pilates. This workout alternates forward/backward moves while constantly adjusts body positions to increase variety as it works multiple muscles at the same time (e.g. in one series, Mari works your muscles from six different positions). Throughout, the band works your muscles in both the extension and contraction movements like an expensive Pilates Reformer machine. It also encourages a larger range of motion and increases control. The bands resistance is adjustable, depending on how its positioned/folded.
• COOKBOOK (128 pages, color, spiral bound) – booklet contianing Chapter 1: Winsor Dozen a “go-anywhere” routines with pictures and instructions. Chapter 2) Body Sculpting Plan. Chapter 3) Win in 10 Exercise Planner. Chapter 4) Win in 10 Meal Plan & Cookbook. Chapter 5-9 Recipes for Breakfast, Lunch, Side Dishes, Main Dishes and Snacks!

Product Description
2 DVD SET INCLUDES THE FOLLOWING: DVD 1: Winsor Pilates Back Workout (20 minutes) is for women and men who want to build a stronger, more flexible back. You can also use this workout if youve purchased other Winsor Pilates workouts because this workout focuses exclusively on your back. Mari Winsor designed The Back Workout so that in 20 minutes you will: (1) Increases flexibility and loosen up the tight areas of your back. (2) Develop muscle strength so that you fee… More >>

WINSOR PILATES 2 DVD SET + RESISTANCE BAND + COOKBOOK. SCULPT YOUR BODY SLIM FASTER!