Implied-in-fact contracts are actual contracts formed by the conduct of the parties, whereas quasi-contracts are implied by law to prevent unjust enrichment.

Quasi-contracts are based on the principle that one person should not be unjustly enriched at the expense of another.

In a quasi-contractual relationship, the legal obligation of the parties is to prevent unjust enrichment, rather than to perform the terms of an express contract or to pay damages for breach of contract.

Quasi-contracts are contracts implied by law to prevent unjust enrichment, whereas written agreements, verbal promises, and court orders are not quasi-contracts.

The legal remedy available in a quasi-contractual relationship is restitution of property or benefits received, rather than rescission of the contract, damages for breach of contract, or specific performance of the contract.

Knowledge of the benefit by the defendant is not an element of unjust enrichment, whereas benefit conferred on the defendant, absence of a valid contract, and detriment suffered by the plaintiff are essential elements.

The primary difference between a quasi-contract and an implied-in-fact contract is that quasi-contracts are implied by law to prevent unjust enrichment, while implied-in-fact contracts are created by the conduct of the parties.

The doctrine of unjust enrichment is based on equitable principles, which seek to prevent unfairness and injustice.

Specific performance is not a remedy for unjust enrichment, as it requires the defendant to perform a specific act, whereas restitution, damages, and injunction are all remedies that seek to restore the plaintiff to the position they were in before the unjust enrichment occurred.

The measure of damages in a quasi-contractual action is the value of the benefit conferred on the defendant, rather than the amount of the plaintiff's loss, the reasonable value of the services rendered, or the amount of the defendant's unjust enrichment.

Lack of consideration is not a defense to a quasi-contractual action, as quasi-contracts are not based on consideration.

A quasi-contractual obligation can arise even if there is an express contract between the parties, if the express contract is unenforceable or if the quasi-contractual obligation arises from a different set of facts.

A buyer and seller relationship is typically governed by an express contract, whereas a landlord and tenant relationship, an employer and employee relationship, and a doctor and patient relationship can all give rise to quasi-contractual obligations.

The statute of limitations for a quasi-contractual action varies depending on the jurisdiction, as it is not a statutory cause of action.

Quasi-contracts are always implied by law, as they are not based on the agreement of the parties.