I will be honest...I haven't tried them side by side and I haven't eaten either one in decades, so I am going to refer to an article on Mashed that compares the two. It states:
"The ingredients in Canadian Kraft Dinner look similar at first: pasta, cheese sauce, and the same spices for color (via
Amazon). However, two ingredients in Kraft Dinner are noticeably absent from the American version: Cheddar cheese and butter. "
Read More:
https://www.mashed.com/634065/is-th...-and-kraft-macaroni-cheese/?utm_campaign=clip
It goes on to say that "when BuzzFeed held a taste test between the two, Canadians overwhelmingly chose Kraft Dinner and Americans stuck with Kraft Macaroni & Cheese." That right there indicates to me that there must be some type of difference and that people prefer the one they have been raised on.
What I can definitively say, is that there are a number of products that carry the same labels in both Canada and the US, but which have different recipes/flavour profiles that are noticeable between the two countries. For example, my daughter can actually smell the difference between Lipton chicken noodle soup (the dry packet version) simmering on the stove and finds it a very different taste, between the Canadian and American versions. I also have a friend that used to bring back cases of Campbell's Cream of Mushroom Soup, because the Canadian recipe tasted better than the American version. While products between the two countries look similar, I would never out-right assume that they taste identical.