Plus its armored with bone plates

Exactly. Though I think the difference is teeth can be pulled out

Actually, there are numerous differences. For instance, bones are living tissue, while the majority of the tooth is not (their dentin and pulp are). Because bones are living tissue, they can heal, whereas a damaged tooth cannot. Their overall composition differs, with bones being mostly structural proteins (also some hematopoietic and stromal tissues) with a minority being minerals and teeth being almost entirely minerals. Also, bones arise from the mesoderm and teeth from the ectoderm. I am too lazy to look it up, but I am 80% sure there are plenty of animals with teeth fused to their jaw bones and are not removable, though.