Gonna try to sketch the etymology of these Vision & Augmentation Systems, In the Beginning was TALOS (Tactical Light Operator Suit) and TALOS was good ...

as a jumping off point for further development, shedding some capabilities, adding others. Armor lighter, weight bearing and an improved AR Vision system. But they couldn't get the ruggedized version of the a slimmed down AR system fast enough into the hands of hyper-enabled operators much less the units that would have to enter those caves in numbers in the event of war. So ENVG grew in capability adding stereo-optic, white phosphor, true AR, Thermal and Digital Night Vision Fusion. And it was good but too heavy.
Now IVAS aspires to do all that in a much smaller package. The recent issue of ARMY Magazine has an article on CFT and in it describes ENVG-B and IVAS in sequence. Leaving me to believe that they are improved iterations of the previous like ENVG-I-II-III. Gen Richardson said IVAS has "PhD level" night vision. PhD NV in Oakeys? Like ENVG-B, IVAS is being made to integrate with RTA/FWS. Some day the soldiers designated will use the same device to train and to use in the field.
 Pull back the camera. Sculley did an "All of them" on the military too.
 Who made an Night Vision System that was digital, no "green glow" from phosphor, no Intensifier Tubes, flipped up, could record? I have one, it sucks, unreliable as to footfall on uneven ground, distance and resolution leaves something to be desired, no color. First one though out in the world.

https://www.defensemedianetwork.com/stories/from-socom-iron-man-suit-to-hyper-enabled-operator/