vitargo is otherwise known as waxy maize starch, a high molecular weight carb that is absorbed faster in the stomach and great as a nutrient transporter. it is usually mixed with creatine monohydrate and used pre, during, and post workout, or simply as post-workout.
sizeon uses maltodextrin and other carb sources, and various different creatines. it is used during, and post-workout as well. i've tried both and both work extremely well. it really comes down to what you want to do...