Reconditioned iphone definition

Is there an official Apple Corp definition of what a reconditioned phone is? My wife had to get her new Iphone 6 (purchased 5 months ago) replaced at the Apple store/Genius bar today due to an assumed "hardware" issue based on their assessment. Apple replaced the existing phone with a reconditioned one. They indicated it was not a refurbished phone but a reconditioned phone. I would like to know what this is specifically. For example, are there any potential "used" part in the reconditioned phone like what a refurbished unit would have? It seemed like I got conflicting responses from the tech that helped us and the store Manager. I just want to make sure I truly understand what a reconditioned phone is actually. Thanks.