The term "implied contract" can refer either to a contract implied in fact or to one implied in law. See Jaqua v. Nike, Inc., 125 Ore. App. 294, 297-98, 865 P.2d 442 (1993). The two concepts differ substantially, and the failure to distinguish them has sometimes led to confusion. See Arthur Linton Corbin, 1 Corbin on Contracts 19 at 44 (1963). An implied-in-fact contract is no different in legal effect from an express contract. Restatement (Second) of Contracts 4 comment a (1979). The only difference between them is the means by which the parties manifest their agreement. In an express contract, the parties manifest their agreement by their words, whether written or spoken. Id. In an implied-in-fact contract, the parties' agreement is inferred, in whole or in part, from their conduct. Id. Other than questions of proof, the two types of contracts have the same legal effect. In both an express contract and an implied-in-fact contract, the plaintiff is ordinarily entitled to recover benefit of the bargain damages. See Sullivan v. Oregon Landmark-One, Ltd., 122 Ore. App. 1, 856 P.2d 1043 (1993) (express contracts). "An implied contract can arise only where the natural and just interpretation of the parties warrants such a conclusion." Owen v. Bradley, 231 Ore. 94, 103, 371 P.2d 966 (1962). Frequently, implied in fact contracts arise because an accepted course of conduct would permit a reasonable juror to find that the parties understood that their acts were sufficient to manifest an agreement. See Restatement (Second) of Contracts, 4, comment a, illustrations 1 & 2 (1979). The term implied contract has also been used to refer to contracts that are implied-in-law or quasi-contracts. "A quasi contractual obligation is one that is created by the law for reasons of justice, without any expression of assent ." 1 Corbin on Contracts 19 at 46. The category includes a variety of types of contractual obligations that are implied to prevent injustice, and the remedy for an implied-in-law contract may be less than the benefit of the bargain damages ordinarily available for breach of an express or implied-in-fact contract. 1 Corbin on Contracts 19 at 49-50.