Cubic zirconia or CZ has always been a competitor with moissanite. However, they're actually incredibly different!
Moissanite is tougher and harder than cubic zirconia.
Toughness is defined as how difficult it is to chip or break something. Moissanite is over three times tougher than CZ. The problem is that cubic zirconia has a very high change or chipping or breaking within someone's lifetime. Moissanite is past the threshold to where you almost never have to worry about your jewelry ever being damaged the same way. Moissanite is also 219% harder than CZ, which means that it is much harder to scratch.
Moissanite has superior visual aspects to cubic zirconia.
Moissanite has a refractive index that is 25% higher than CZ, which gives it that sparkle effect in the light. Not only does it have more of this effect, but the effect itself is more desirable. For instance, moissanite has a higher dispersion rate than cubic zirconia. This makes more of that fiery, flashy, rainbow colored light. Moissanite also has has 49% more luster than CZ, which is the amount that is emitted from the surface of the stone.
Moissanite is more resistant to dirt than cubic zirconia.
Over time cubiz zirconia jewelry will start to become slightly cloudy. This is because it is much more susceptible to hand oils, cosmetics, and other things in it's environment. Moissanite is not only more resistant to these elements than cubic zirconia, but it's more resistant than diamonds themselves! With CZ, you'll have to hard clean your jewelry every few days!