In the United Kingdom PhD degrees are distinct from other doctorates, most notably the higher doctorates such as D.Litt. (Doctor of Letters) or D.Sc. (Doctor of Science), which may be granted on the recommendation of a committee of examiners on the basis of a substantial portfolio of submitted (and usually published) research. However, most UK universities still maintain the option of submitting a thesis for the award of a higher doctorate.
Recent years have seen the introduction of professional doctorates (D.Prof or ProfD), which are the same level as PhDs but more specific in their field. These tend not to be solely academic, but combine academic research, a taught component and a professional qualification. These are most notably in the fields of engineering (Eng.D.), education (Ed.D.), educational psychology (D.Ed.Psych), occupational psychology (D.Occ Psych.) clinical psychology (D.Clin.Psych.), social work (D.S.W), nursing (D.N.P), public administration (D.P.A.), business administration (D.B.A.), and music (D.M.A.). These typically have a more formal taught component consisting of smaller research projects, as well as a 40,000–60,000 word thesis component, which collectively is equivalent to that of a PhD degree.