nivlac’s right. You really have to know that program requirements differ greatly so it is difficult to generalize, but typically an Ed.D. is a practice-oriented degree while a Ph.D. is research-centered. Some institutions (Florida State, for instance) offer both Ph.D. and Ed.D. programs. I can vouch for a certain very, very old institution near Boston that the only terminal degree in education is an Ed.D., which requires a qualifying paper, a thesis, and oral examinations - the exact structure of a Ph.D. program, and in fact, the template for many Ph.D. programs in education across the nation. (A friend is in the Ph.D. program at Boston College and I compare notes - we’re doing essentially the same thing.)
Because of plain laziness and people’s reluctance to learn what exactly people do in their programs, some Ed.D. graduates from my school (specifically, ones who are in the human development and psychology department) encounter difficulty when applying for NIH grants that say “Ph.D. only.” Typically this is resolved by a letter from prominent faculty explaining that this particular program has the same requirements of a Ph.D., or in many cases, people know that this institution only grants Ed.D. degrees.
At my institution, only the Faculty of Arts and Sciences can bestow the Ph.D. degree. For a Ph.D. to be a reality for me and my cohortmates, we would essentially have our educational careers managed by folks in other academic disciplines rather than education researcher. Most of us prefer the arrangement now, but if plans to create an Ed.D. practitioner track and a Ph.D. research track come to fruition, I hope to be very, very far away…
Ultimately, I’ve been assured that research experience, publications, and teaching trump the letters after one’s name. Good institutions will value Joe Blow, Ed.D., if Joe authors papers and presents at research conferences. Richard Roe, Ph.D., won’t be at an advantage if he just writes a thesis and heads out of town.
Despite what twicks and silenus said, it takes about 5-8 years on average to complete an Ed.D. here. At this institution, your thesis is required to be an original contribution to research and/or the literature on an item of interest. You have to go through many hoops to get to the point where you can propose a thesis topic, so you can’t just come up with something out of thin air…