Condition, stipulation, terms, provision, proviso, reservation, strings are comparable when meaning something that is established or is regarded as the prerequisite of a promise or agreement being fulfilled or taking effect.
Condition implies the laying down of something as a prerequisite which must be observed or satisfied if the validity of the whole agreement, promise, dispensation, or gift is not to be destroyed.
Stipulation differs from condition chiefly in implying a formal, explicit, and often written statement (as a contract) binding a party thereto to a specified course.
Terms indicates conditions offered or agreed upon by one or both parties to a contract, agreement, or deal; thus, two parties may come to terms (i.e., may agree upon such a matter as work to be done, prices to be paid, or a division of property).
Provision applies chiefly to a documentary statement which provides measures for the treatment of certain matters legally. It may be specifically used of a clause or of a part of such a document or of a document that is comparable in laying down a condition or making a stipulation.
Proviso denotes a condition or a stipulation, especially one that is clearly stated and binding.
Reservation indicates a qualification or modification of the terms of an agreement or statement, often to cover contingencies. It may become a stipulation or proviso if the other party or parties concerned agree or acquiesce or it may be avowed only to oneself in evading the generally understood sense of a promise or an oath or other statement that one is impelled to make for reasons of necessity or expediency.
Strings suggests strands which the maker of a promise, a proposal, or an offer keeps in his hands so that he may pull them back if what he lays down as a condition or imposes as a stipulation is not kept; the term usually denotes conditions or provisos, often unexpected or concealed, that may radically alter or even annul an agreement.