Harvard University granted the first Ed.D. in 1920 after recognizing a need for more educators to have doctorates. The Ph.D. is based on the German practice of awarding a doctoral degree to students who complete a course of graduate study, culminating in a dissertation of original research.
In theory, the Ph.D. in education focuses more on research, while the Ed.D. emphasizes educational practice.
Universities award Ph.D.s in many academic fields, including education, while the Ed.D. is limited to the discipline of education.
Within the field of education, the Ph.D. emphasizes greater breadth and depth in theory and research methodology. The Ed.D. focuses on educational leadership and the application of research.
Research on Ph.D. and Ed.D. dissertations in education found that the former emphasized experimental and quasi-experimental research designs, using statistical methods. Ed.D. dissertations were more descriptive, using surveys and related methods.