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.
The specific interpretation is how I use it: if it’s bread bits cooked inside something, it’s stuffing, and if it’s bread bits cooked outside something, it’s dressing. If it’s bread bits cooked on its own, it’s croutons and is now reserved for salads.