l know 2 ways how to check your render licence. Please se pictures below.
There are many differencies between ARX and Photorender.
From main point of view the main difference are HDRI scenes. ARX use HDRI scenes (HDRI scenes are a standalone topic).
These "picture" is a source of light. See youtube link:
Vray HDRI tutorial in 3ds Max - YouTube
Sky and sun in background are HDRI scene "picture".
As you can see in time 5:15 the HDRI becomes a part of final render picture ---> is reflected in swimming pool and makes a building lighter from right side.
Vladimir Palfy (my rendering guru) create great topic how to make your own HDRI scene.
Tutorial: HDR library for Rendering of your CAD design - GrabCAD
In general ARX is much more realistic than Photorender.
Hope it can helps you