Very interesting. A couple observations:
1. The muscle composition of the 250lb female appears like it is more "puffy" or contains more air/water.
2. The lungs of the 120lb female appear clearer, which is interesting, because it may indicate that fat is even encroaching on the lungs of the 250lb female & making them darker.
2a. On the other hand, it may simply be that the lungs of the 250lb F are compressed, and thus appear darker in these images.
3. The bone structure to muscle ratio on the 120lb F seems more "efficient" in terms of body composition. It doesn't look like there is "wasted space" in the 120lb F's body, because of that.
4. Interesting that you can clearly see the spine of the 120lb F, but only barely make it out on the 250lb.
5. The esophagus of the 250lb F appears to be causing a "dip" in her stomach, whereas the 120lb F esophagus appears off-centered, and only connected at 1 point.
I'm curious as to the reason for why we can see the "innards" of the 250lb, but not the 120lb. Perhaps this relates to core muscle mass being more dense and not providing as much "transparency" with the "Dexa scan" ?