I'm pretty sure one is the Pentax, and two is the Sigma. It's the colors that do it for me. The Foveon renders color in a more subtle, matter-of-fact way, and continues to look different no matter how much you process the picture.
Also, the clouds are a good clue. I know you said they're moving, and the two pictures aren't of the same sky, but I don't think a Bayer camera would render the clouds the way they look in two.
Detail between the two is so similar, I wouldn't judge based on that. These cameras are
very close in resolution. One looks ever so slightly bleary compared to two, but it's so subtle, I might be imagining it. Confirmation bias and all, you know.
Thanks for doing this,
panoguy. I'm looking forward to your full comparison. Get ready for people to call your lenses bad, decentered, misfocused, etc, etc...