Both of them have certain legal effect.

A contract is an agreement between civil subjects to establish, change and terminate a civil legal relationship.

Contracts established according to law are protected by law. A legally established contract is legally binding only on the parties, except as otherwise provided by law.

Contract is an objective requirement to adapt to the private ownership of commodity economy and a legal form of commodity exchange. After the production of goods, people gradually formed many habits and rituals about exchange in the long-term exchange practice for the safety and credibility of exchange.