Here's the procedural terrain. As you can see, there are some obvious artefacts at the rear edge of the terrain, also there's one on the right hand side which you can't see but which is casting a very obvious shadow.

Rutra,  I think the reason you don't see them is that you've got Zero edges turned on. If you turn that off, you'll see artefacts, I'm fairly sure. Anyway, they are removed by setting the scale to 1.01 (I haven't shown that but can do if anyone wants to see it).

As to whether there's any real difference in quality between the two images... frankly, I think not.

Steve