Here ya go, Breezy:
http://www.ilovecheese.com/cheese_profile.asp?Cheese=Cheddar
I clicked on C for Cheddar, not the recipes.
The difference is taste, texture, color and melting. Aged cheeses will have a different taste as well. If you're using cheese to dump in a mac 'n cheese casserole, I imagine the color does not matter as much as the taste & how it works with the rest of the ingredients in the recipe. If you're buying the shredded stuff in a bag, yes there is a difference in taste and the crap that's added in. Just read the label.
I find white has a nuttier flavor, & orange pj's can range from mild to sharp. In short - there is a difference in flavor. And, please, don't buy that processed stuff. Who knows what color it started out with. I pay a lot of $ for good cheese at a deli counter, freshly sliced, & know what I'm getting.
Another example - mozzarella - you can buy fresh (the best), or that plastic stuff in a ball. They're both white, but miles apart in taste.
BTW, if you're making a mac n cheese casserole, try Gruyere and add some spinach.