What is the difference between cofactors and coenzymes?

Cofactors are non-protein molecules required for enzyme activity. Metal ion cofactors (Zn2+, Mg2+, Fe2+, Cu2+) are inorganic and often participate directly in catalysis or stabilize enzyme structure. Coenzymes are organic cofactors, often derived from vitamins: NAD+/NADH (from niacin) for redox reactions, FAD/FADH2 (from riboflavin) for oxidations, coenzyme A (from pantothenic acid) for acyl group transfer, and pyridoxal phosphate (from B6) for amino acid metabolism. Prosthetic groups are coenzymes tightly bound to enzymes. Coenzymes act as chemical group carriers, accepting groups from one reaction and donating to another.