I was looking over the website and, to be honest, can't see much difference in the profile of the adult vs pup food.
Each seem to range from 28-32% protein (+/-).
It seems to me the grain free/high protein diets are very similar in the adult/pup lines?
Is the Aussie eating large breed puppy food or just puppy food? If it is large breed puppy food, then there is probably a difference in the calcium. If it is just regular puppy food, then it's probably pretty similar.
I feed large breed puppy food to puppies until they are about 1 year old, and then switch them over to adult. They are a little bit bigger than Aussies, though, so this might not be relevant.
I fed my black lab large breed puppy food (Wellness) until he was 15 months.. at which point I switched him to a grain free adult food, currently Acana. My general rule of thumb is that the bigger the breed the longer they should stay on puppy food.