Moissanite vs Cubic Zirconia
Moissanite is silicon carbide, a compound with chemical formula SiC. On the other hand, cubic zirconia is zirconium dioxide, ZrO2. Moissanite is composed out of silicon and carbon, whereas CZ in its crystal lattice contains zirconium and oxygen. If you compare both of them to diamond, moissanite comes much closer.