这两个单词均有发誓作伪证之含义。其区别在于除其各自为普通法上的单独犯罪（apart from being separate offenses)外， 且forswearing的范围较perjury广，其可泛指任何场合下发誓人明知不是事实而发誓确认之情况，故为刑法规定之“伪誓罪”， 等同 false swearing或false oath，其罪行较 perjury轻[1]。而 perjury为“伪证罪”，是普通法上的轻罪（misdemeanor)中情节严重的犯罪，其为一技术术语，专指在主管法院或官员面前发誓说假话，且所涉及问题均为实质性问题，这两点都是forswearing不必一定包含的因素[2]。perjury还涉及到有关道德等因素，这 同样也与forswearing无甚关系[3]。

[1]“The crime of making a false statement under oath or affirmation，other than in the belief that what is being said is true. A broader and less serious offense than perjury. " Cf. James E. Clapp，Random House Webster's Dictionary of the Law, at p. 178, Random House， New York (2000).

[2]“Forswearing is wider in its scope than perjury，for the latter, as a technical term，includes the idea of the oath being taken before a competent court or officer，and relating to a material issue, which is not implied by the word forswearing. ”Cf. The Publisher's Editorial Staff, Black's Law Dictionary，abridged 6th edition, at p. 451，West Publishing Co. (1991).

[3]“The technical difference at common law between perjury and forswearing, apart from their being separate offenses, is that perjury connotes corruption and recalcitrance, whereas false swearing connotes mere falsehood without these additional moral judgment. ”Cf. Bryan A. Gamer, A Dictionary of Modem Legal Usage, 2nd edition, at p. 652, Oxford University Press (1995 ).