Not the same.
I completely agree with their conclusions. Muffins are heartier, often with bits of fruit or nuts and much denser - especially if, when you eat muffins, you tend to go for fiber blueberry or peach raspberry, like me. Both have bits of fruit that could potentially lend themselves towards being a cupcake, but who's ever heard of a fiber cupcake?! Nobody.
Also, I agree with Cakespy that frosting is a key deciding factor. As Cakespy pointed out, cupcakes always have frosting. Frosting makes them special, makes them cute, and makes them delicious. Muffins, on the other hand, do not have frosting. The line is slightly blurred when you have a muffin with that lemony, creamy glaze topping, but I think those are hybrids. My bet is that either the baker who makes glazed muffins for your favorite coffee shop goes home and night and makes cupcakes OR the glazed muffin maker knows their muffins are subpar so they put the glaze on in an attempt to make up for shortcomings. One last thing it is important to note, however, is that a cupcake without frosting ISN'T a muffin. It's a lamecake. A big, caloric "why bother".