This is how I would define it. And this is quite basic.
If you build a tank or plane, what ever, it doesn't matter, and you follow all the basic rules of modeling, fill the seams, check allignments, no glue showing, prime it and paint it basically, as if right out of the paint factory and say its finished, your a modeler.
When you cross the line into artistry, and again, this is just my opinion, is when you take the time to study weathering effects, effects of light and shadowing, acurate skin tones for the region, and for some of us, the ability to convey proper textures, and you apply them consistanlty throughout your model, I believe that's when you've crossed the line from being a basic modeler into an artist.
I've seen sand bags on Armorama sprayed with one color and I'd say to myself, oh, its a sand bag. But then I see another person's sand bag and I just wanna copy that photograph for my personal library because this persons sand bag was beautiful. It had highlights, shadows, textures that resembled burlap. It even had an area that you could tell the sand and burlap was still wet from previously being wet. The sand bag showed imagination, it told a story and yet, it was just a sand bag.
I hope this helps.
