Superficially the difference is the plastic body on the 0450 vs the metal one on the 0480.
Also, the 0480 has an extra power switch position.
With the 0450 you have to press the group handle against a button under the spout to activate the grinding action after the power is switched on.
I believe the 0480 also has a manual on setting so you can grind into a container without having to hold it against the button.
The burrs are supposed to be identical but the motor of the 0480 must be better because I think theres a 5 year warranty on the 0480 that the 0450 doesnt have.
Also theres a $50 bigger price tag on the 0480.
Ive havent any experience with the 0430 but have been led to believe they arent as good as the other two, which means dont bother with the 0430 as the others are the minimum recommended for espresso grinding.