If you're anything like me, you have NO IDEA of the different "types" of exercise or when you should do which. I'll let @PFungFitness provide details later, but for now, I'll share what I've read :)
After reading an article in the New York Times about combining aerobics + weight training, I've learned... to do what I wanna do :) A group of scientists took two groups (over an extended period of time) and tested the issue at hand. One group did aerobics one day + weight training the next. The other group did both in the same day.
Hypothesis: Combining Aerobics and Weight Training in the same day would change the physical outcome of the workout.
Result: No difference -_-
You can read the article full-out if you want to, but I wanted to summarize for you all :) Plain and simple, there is no real difference in the physical outcome, but I'd assume the limit of the amount of exercise you do would make an impact. When I work out, I don't do any more than my body can. Occasionally I push myself, but I find working out more enjoyable when I'm comfortable with what I'm doing.
Mix away & enjoy your workout! :)