Question

How are prosthetic groups different from co-factors?

Answer 1

Definition

Cofactor is a non-protein part of conjugate enzymes that may be loosely or tightly bound with the apoenzyme.
Prosthetic group is a type of cofactor that is bound tightly with the apoenzyme.

Examples

NAD is a cofactor of many enzymes involved in redox reactions.
Haem is a prosthetic group in peroxidase and catalase enzymes.