Difference between executory executed and past consideration?

EXECUTORY CONSIDERATION Consideration is executory when there is an exchange of promises to perform acts in the future. For example, A promises to deliver widgets to B at some future date and B promises to pay A for the widgets when he receives the shipment. If A does not deliver the widgets to B, B can sue A for breach of contract. EXECUTED CONSIDERATION When a promise is made in exchange for an act, when that act is performed, it is executed consideration. Using the example above, if A timely delivers the widgets to B, A's consideration becomes executed. PAST CONSIDERATION Every contract requires an offer, acceptance, and consideration. Consideration isthe exchange of benefit and detriment (e.g., the making of a promise in exchange for an act). If a party voluntarily acts and then the other party makes a promise, the act is said to be "past consideration" (since the act was already performed and not made in exchange for the promise). For example, A gives B a ride to the market and back home again. When A delivers B to his house, B promises to give A some gas money. A cannot sue B to enforce B's promise since the consideration (A's act of giving B a ride) occurred beforeB's promise. A gave B the ridewithout expecting anything inreturn.(A did not give B a ride in exchange for B giving A gas money.)