IMHO... Mac and cheese is a side, but as soon as you start adding other stuff to it though, especially meat (or standin proteins for the vegetarian crowd), it starts crossing into "pasta" territory.
The only real difference at that point is cheese selection, as you could easily use an alfredo on any noodle shape, including elbow macaroni. Is it really that different because it uses a cheddar-blend base?
Personally, I'm a fan of a good macaroni with a meat sauce on top. You can either make it as cheap and easy or as fancy as you like simply by swapping out your ingredients.
Like... whole wheat pasta, with cheddar and smoked gouda, and shredded barbecue beef on top
