Honestly for me, it's simply a matter of how it's cooked. If it's "stuffed" in the bird, it's stuffing. If it's in a dish on the side, it's dressing. But I do reserve that stuffing can be pulled out and served on the side. And you can also eat stuffing without ever "stuffing" it. Stove Top Cornbread Stuffing is my weakness and I use it as a quick and easy side often with a protein. Or when making crab cakes.
I agree with your take on it but I'd like to add this as well.
Stuffing is both the act of and what is going to be put into the cavity of whatever animal. Dressing is the stuff that's going to get stuffed into the cavity of whatever animal so really there is no difference. It may also be a regional thing as I never hear anyone call it dressing where I'm from.