Both have adjustable temples and are very comfortable. The Ultraspecs are not adjustable but have great coverage and probably the best peripheral vision of any safety glasses. They are not terribly comfortable and fog up easily, however. The old-style AO glasses are perfect for that 50's dweeb look and don't fog up because of all the ventilation. The Flexi-fit aspect is that you can bend the temples to your heart's desire because they have a metal wire running down the center.
Peripheral vision is terrible.
They are pretty comfortable. Boy are they super-nerdly looking. Two colors worth of AO Aerosite glasses. You can bend the temples if you soak them in hot water, but then they don't fit your ears. I have at least 15 pairs.