Well, i don't know the technical difference between the two, but i know the videophile difference i practice between the two.
A few months ago i sat down with 3 others to do a 1:1 comparison of the two. My own thinking was that this was the same wine in two different bottles, where the main difference was the label itself. But i was proven wrong.
First off all we calibrated both machines, incl. white balance using measuring equipment. From factory "our" BW2 needed less tweaking than "our" HD1, and the numbers, ended up just a little better on lumens and contrast on the BW2, but not by much. In practice, with our own eyes, there was no real difference to recognize when doing the 1:1, when we are talking lumens and contrast ratio.
However there was the other, and more subtle videophile differences to acknowledge. When it came to shadowdetails, or perhaps rather all the microdynamics in the picture, the BW2 simply painted us a more alive and dynamic picture. We were simply made much more aware of all the subtle differences and nuances in the picture, and this was actually true for both film and even animation material alike. The nuances was just standing more out, and staring us more directly in the face.
To put it more plainly, the HD1 looked a bit more "clinical", timid and "data-projector" like (Compared to the BW2 not to forget
), while the BW2 looked like a more determined video projector.
I don't know what it is Barco/Cineversum have done, but somehow they must have managed to incorporate some of their high-end and professional video projection experience, in optimizing on their own version of the JVC projector, when comparing it to the HD1.