PhD programs of medical school I'm interested in stem cell, regenerative medicine, developmental biology, and genetics for reverse aging. Since these topics are dealt with in one or both of medical school and school of science, I'm confused about my grad school prep. 

A PhD program of stem cell &amp; regenerative medicine offered by Stanford's School of Medicine accepts both MCAT and GRE (as stated in the following webpage.) http://stemcellphd.stanford.edu/faqs.html 
Also, the PhD program of my interest offered by Harvard belongs to both Harvard Medical School and School of Arts and Sciences. Thus, the boundary of PhD programs between medical school and school of science doesn't seem to exist. So, I'm thinking if I can prepare for PhD programs of med school in the same way as I do for programs of school of science. 

Would you tell me the difference of PhD programs between med school and school of science in terms of the following factors?


standardized test (GRE &amp; MCAT)
admission standard (focus on research experience or focus on GPA &amp; standardized test) 
competitiveness 
undergrad classes required/recommended to take
In general, the biggest difference between PhD programs at med schools and those not at med schools is simply their research focus. Often they have differences in the administration and faculty associated with the program, but at least for Harvard (that's where I just finished my PhD), the difference between the med school programs and those not at the med school is probably smaller than the difference between Harvard's med school programs and Stanford's med school programs.

Each PhD program is different, and may have different requirements in terms of admission and selectivity, but for the top tier of graduate schools, the difference is probably not hugely noticeable. There are also likely to be differences between say the Immunology program at Harvard and the BBS program, even thought they're both at the med school. 

I can't speak to Stanford, but at Harvard, your GPA and GRE's will have some influence, but your research experience and letters of recommendation will hold far more weight. 

I'd say, apply to the programs you're most interested in, and then if you're invited to interview, make your decisions after you've visited the schools. You want to base your choice on the feeling you get from the students and faculty - different programs align more with different personalities. If you're choosing between Harvard and Stanford, you won't be choosing between different qualities of research (both institutions are phenomenal), you want to go where you'll be happiest because of culture etc. 

Edit: Spelling