when you understand the fundamental /technical aspect of photography, composing and lighting, what else do you need to know in order to say you're an expert photographer?
The "what else" is knowing how to put all these aspects into practice. I tend to break these up a bit differently.
First the technical: Exposure, focus and the like... this all must be learned so that's "second nature." This part is MUCH simpler now with the advances and ease of modern equipment. Once you really have all that down, then you are freed to concentrate on the next part.
Then the art: composition, lighting, posing and so on. This part can be tougher to learn. Doing it over and over and over, one will begin to refine these concerns. Perhaps the hardest part of this is never to compromise. Much like making a painting, it's you who must decide everything in the composition... placement of elements, colors, etc.
can anyone provide an image of such caliber and explain what make it better than another in comparison?
Let's go another way. If you would provide an image you made that you feel represents your current efforts, I (and I'm certain MANY others) will offer a critique. Self-critique is tough.
I'm pleased to hear you're thinking about how to grow in your craft.
-Pete
ONE MORE THOUGHT: For this discussion, perhaps it's best to stick with "conventional" wisdom... what's is considered to be excellent in our industry.