Solution:According to Section 2(B) of the Indian Contract Act, 1872, when the person to whom the proposal is made signifies his assent thereto, the proposal is said to be accepted. A proposal, when accepted, becomes a promise.
Offer is an open invitation by the promisor for the acceptance of the terms and conditions of the undertaking, which when accepted by the promisee becomes binding on both parties and the proposal becomes a promise. Hence the difference between an offer (proposal) and a promise lies in acceptance of the offer (proposal).