Difference between 3 campy 80mm deep section wheels
The najor difference is that Bora wheels are full carbon while Bullet are both aluminium rims with carbon profile. Also Bora wheels are tubular and Bullet are clincher rims. Still Bora are considerably lighter. And they have carbon hub bodies.

As for these 2 Bullet models, as you said Ultra are slightly lighter; not sure where the weight savings come from though...