When Augustus started his military campaign he conquered more lands than Caesar did. Through Augustus's military campaigns he conquered the whole of Spain and Gual, and big parts of modern day Austria, Hungary , Bulgaria and Romania. Augustus reformed parts of he Roman army, he added the Praetorian guard, which guarded the emperor, this army consisted of 9,000 men.
Caesar started big reforms in Rome and was a great leader that was the spark of a new Era , but Augustus was the one to take all Caesar has created and go further, he was the one that made Rome, so succesful. When we think of ancient Rome we think of what Augustus created.