Stuffing goes inside the animal you’re roasting.
Dressing, in my head, goes on top of the food, kind of like a salad dressing. I’d think of cranberry sauce as dressing.
But… apparently, some people use it to mean stuffing. When you google “turkey dressing,” you get the same images.
The confusing thing is that the dressing/stuffing is not always stuffed in an animal. Some people are perfectly happy to eat the “stuffing” even when it’s not stuffing anything.
Maybe that’s how the word dressing came about?
Where I live, everyone says stuffing, though.
So, the final answer is that they’re the same thing, called differently in different places.