The Phd and PsyD are both doctoral degrees — the PhD being designated to any doctoral degree while the PsyD designated purely for psychology. A person can still have a PhD in psychology and a PsyD is not the only doctoral degree for psychology. The two vary in their specialization and practice.
A PhD in psychology is generally focused more on research than on clinical work. The PhD program is designed for psychologists who want to do research and also apply it. Some PhD programs emphasize creating psychological scientists who can advance the field of psychology from research. The PhD program also allows the student more freedom to study niches of psychological theory, rather than the broad strokes.
The PsyD in psychology is focused more on training the psychologist for clinical and therapeutic work. Less emphasis is places on research and more on how to apply knowledge in the field. PsyD students must be very familiar with the methodologies, research and theories of psychology and interested in research. However the PsyD students use this knowledge primarily in the field for treating patients rather than in experiments and research labs.
PhD programs are traditionally more well funded than PsyD programs. The reason for this is that PhD students tend to work in research projects with the faculty at an institution. These research projects are usually funded. PsyD students spend more time doing clinical work with patients and there is generally less funding to pay students for clinical work.
PsyD students tend to finish their degrees more quickly than PhD students. While they both require a certain number of hours, years, courses and dissertations, the thesis for the PsyD student tends to be simpler than that of the PhD student. The PsyD student can choose a practical topic from his clinical work to focus on. The PhD student has to devise a research topic that has not been attempted before and carry out the research, defend it and contribute to the advancement of the field. This can take several years, especially if the research relies on an experiment that takes several years of study to complete.