1 gig ram
dual core
qhd 960x540 (or whatever it is)
Besides some small differences in actual screen dimensions and size of phone, Photon/Atrix/Bionic are practically the same phone. The only difference I could think of of any significance (and it may or may not be much) is that the Atrix/Photon have the dual core Tegra 2, and the Bionic might have the dual core TI OMAP? Someone correct me on that please, as I haven't dug much yet.
A few off the top of my head is the tegra vs omap, 1080p vid vs 720p, no mention of gorilla glass in the photon whereas rumors have pinned that on the bionic table.
Although there are dual core there can and probably will be a significant difference in performance. You can compare a similarly clocked intel cpu vs an amd and notice that intel wipes the floor with amd. With the welcoming with open arms that the insiders and knowledgeable mobile tech gurus of the TI chip vs tegra I suspect we will see a greater performance increase over the bechmarks (although im not too crazy about the consistency of quadrant results. While they are similar, I believe that the smaller differences the bionic has still qualifies it to be on the top of the moto mast till the years end. All this without the confirmation of bionic specs so there may even be a treat still in store.