That's just word play. You named a sandwich, its just a common name, still a sammmy.
It's the same thing with squares.
A rectangle is a square but a square isn't a rectangle.
They're similar, but not the same.
I made a thread awhile back, asking what people thought about a hotdog being a sandwich. Most people disagreed but no one could really say why. It's meat between bread. It's a sandwich.