A void agreement is one that lacks legal validity from the beginning. It is essentially no contract at all and cannot be enforced by either party. This might be due to illegality, impossibility, or other fundamental defects.

On the other hand, a voidable agreement is initially valid but has some flaw that allows one party to choose whether to void (cancel) the contract. This could be due to factors like misrepresentation, coercion, undue influence, or incapacity of one of the parties. The party with the power to void can either affirm the contract or choose to void it, depending on the circumstances.