Why all vertebrae are bones but all bones are not vertebrae?

Well, to know the answer to this question, you must know the meaning of vertebrae. Vertebrae are just a connections of bones that make up your backbone. These include about 24 ligaments that make up your spine. So all vertebrae are bones since they are ligaments and other bones that make up, well, your backbone! However, not all bones are vertebrae, because your finger bones, ribs, skull, and other bones in your body aren't part of your backbone.

Hope this helps!