Because awake is clear cut and well understood whereas aware is not.
We don't know what consciousness is and pretending that's a simple question because it's easy to tell when an animal is awake or not is disingenuous at best.
Funnily enough you did not answer the question. Is there a difference between awake and aware? What is it? How do I test if something is awake but not "aware", or "aware" but not awake?