Sorry for the long response...I'm hardly ever on this page
Zeros, witblits and silverbacks are all completely different from each other. Witblits are a patternless mutation, and can retain some color. Zeros are more along the lines of a leucistic. No color, no pattern. Some have dark eyes, some dont. Adults are pure white. Silverback is also a patternless mutation, but does not develop until the dragon is 6-8 months of age. I attached pics of all 3....
top pic: Zero
2nd down: silverback
3rd down: witblits
bottom: plasma(translucent zero)
Kat- Zeros are my favorite out of the 3. Not only are they pure white, the translucent zeros(plasma) are a beautiful lavender/purple.
Thanks!
Josh