Probably just the lighting!

When they're younger the two definitely do have striking similarities with the chevrons on the abdomen and coloring of the metatarsus - in person our irminia is jet black with yellow bands, and our cambridgei is gun metal silver with orange stripes instead of a complete band.She (Chevy) also just molted and nearly doubled her leg span, so she'll be getting a new home soon with about four times the height of her current habitat.
We also just brought home a sub adult H. maculata (Togo Starburst), pictured below in her pet store container. We're doing a 2.5 gallon upright build that should be ready shortly for her to move into.