How does a review differ from an audit particularly in terms of the level of assurance implied by the auditor's report?

How does a review differ from an audit particularly in terms of the level of assurance implied by the auditor's report?
An audit of historical financial statements is a form of attestation service in which the auditor issue a written report expressing an opinion about whether the financial statements are in material conformity with generally accepted accounting principles. When presenting information in the form of financial statements, the client makes various assertions about its financial condition and results of operations. External users who rely on those financial statements to make business decisions look the auditor's report as an indication of the statements' reliability. They value the auditor's assurance because of the auditor's independence from the client and knowledge of financial statement reporting matters.
A review of historical financial statements is another type of attestation service performed by CPAs. Whereas audit provides a high level of assurance, a review service provides a moderate amount of assurance on the financial statements, and less evidence is necessary to support this level of assurance.