It looks like two different engines in the photo gallery, since one engine is more red while the one on the box art seems red in both. Mechanically same and different than the box art for sure. If the box art stayed the same since they were first released, then maybe he used different nv assemblies at one point. Just conjecture, I know no facts on RV's engines.
I was thinking a short while ago about how little I know about all the cox cylinder variations, for having owned and messed with them for so long. I know there are some detailed posts, this reminds me to find them.