a contract is an agreement  between two or more parties that the law will enforce.this agreement  means a meeting of mind called in law consensus ad idem.
every contract is an agreement But every agreement is not a contract

A simple contract has these elements:
1_offer and acceptance
2_consensus ad idem
3_intention to create legal relation
4_capacity of the parties
5_consent must be genuine
6_consideration must be present
7_legality of the object
8_possibility of performance