Nope, there is no difference.

You have a mesh, you have a texture. You have shaders.
You render it, and the result is a picture.
The picture either looks like a photograph or not.

Game environments and meshes used to be very simplistic but not any more.

Those cars for examply are more accurate and detailed than 99% of the Poser cars available.

If a GAME screenshot looks more photorealistic than an hour long Poser/Studio render, then something is wrong IMO.