There are other subtle differences, but it takes some time working with both to really see it. Case in point, another characteristic is eye color. U.sameiti will often have a distinct yellow or orange ring around the "edge" of the eye. You can see it both of your females, but now that I'm looking closer, the ring isn't very bright, per se. It's usually a bit more vibrant than what I'm seeing at the moment.
Here is an example of what I mean in one of our studs:
When I examined a few other images, primarily of females, I notice the ring to be more part of the underside of the eye lid than the actual color of the eye. The ring on the eye still has a bit more color than typical U.sikorae:
You can clearly see it in it this hatchling:
I didn't mean to turn this discussion away from your wonderful animals. The lighter colored female is a stunner for sure and I'm glad I was wrong, for both her and the males sake.
Cheers!
Luis