What is the difference between Charter and Covenant?

CHARTER is the rules and regulations from U.N.O to those states who have joined, joining or will join the United Nations Organization(U.N.O) and meaning of Charter is "A form Document incorporating or joining an Institution or organization and similarly defining the rights and privileges etc of particular institution.

While the meaning of COVENANT is a Contract, means that it is an agreement between two or more than two persons or states to do or not to do something desired, specified or required. The Covenant was main factor for the entrance to the League of Nations and should follow by every state.