In the UK, both are awarded for studies undertaken after gaining a first (or ordinary) degree (eg BA, BSc). They are also called post-graduate degrees and diplomas. A graduate degree is a Master's or a Doctorate. A Master's requires at least 2 years of full-time study. A graduate diploma requires 1 year of study, and can be used as an intermediate step along the way to a Master's degree. (There are other diplomas which can be achieved without having any previous education.)

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degree - an academic award conferred by a university or college on successful completion of a course or as an honorary distinction. diploma - A document issued by an educational institution, such as a university, testifying that the recipient has earned a degree or has successfully completed a particular course of study. A Graduate Diploma is generally a postgraduate qualification, although some graduate diplomas involve the study of undergraduate level courses. The diploma is normally taken following a Bachelor's degree and a successful award allows progression to a Masters Degree without having received Honours with the Bachelor's Degree.