The official languages of Tahiti and her islands are French and Tahitian. Although French is used in schools and business, the Tahitian language is still preferred by most islanders in their homes.
So, a treaty is a kind of executive agreement, one in which two thirds of the senate has provided advice and consent.. That language comes from Article II, Section 2, Clause 2 of the Constitution. This clause defines the procedure and authority for creating treaties. Its text:
With a Purchase Agreement, normally what you find is language that says that as long as the purchase order issued complies with the terms of the Purchase Agreement it is issued under, that order is binding and enforceable. The difference between the two has nothing to do with the time period involved. A Blanket Purchase Order may be for long period and a purchase agreement may be for a very short period. The difference has nothing to do with the volume involved.