Agreement, Accord and Understanding are comparable chiefly in their political and legal uses. They agree in designating a settlement reached by parties to a dispute or negotiation.
All these terms imply concurrence as to what should be done or not done; all imply reconciliation of differences.
Agreement is the most positive word; it usually implies a final settlement of terms. Anagreement may or may not be put into writing (as in the form of a contract or treaty); it may or may not be accompanied by a consideration.
An accord is, in controversies between governments, an informal agreement; use of this term often implies that all details have not yet been settled or that the terms of the agreement are not yet ready for publication, but that the conditions necessary to a final agreement have been fulfilled.
In law an accord is an agreement between the parties concerned in a case where satisfaction for an injury is demanded. The execution of such an accord bars further litigation.
An understanding is the least binding of accepted settlements. If the term is used to denote the final stage in a negotiation or in settlement of a dispute, it implies the existence of definite engagements or the exchange of promises, and dependence on the honor of the parties to the agreement for the keeping of such engagements or promises.