Some gorgeous artwork over there and a very nice result for the airplane!
As for the differences: you have a lot more of control over materials in the major 3d apps, depending on the renderer plugin of course. The most apparent difference will be in the GI and details in non-lit areas, I guess. For example, the fan and the interior of the engine at the front opening lack a proper definition and look rather flat (just an obeservation, not a critique!). Renderers like Brazil, Vray or Mentalray will render those areas with a lot more detail. Terragen's renderer delivers beautiful results on large scale stuff, smaller scale details tend to wash out imo, but I guess it's intended because it couldn't render a planet if it was to take care of a 1m detail.
