If you go DO there are tons of doors that are essentially sealed shut...ACGME residencies of whole specialties (plastics, derm, ent, urology, ortho) and competitive programs in popular specialties (IM, peds, radiology).
This is a fair disclaimer and factually based on residency program director surveys and match results. There is no argument to be made here.
To the OP, you would get more useful answers asking this question in the osteopathic medical student section of the forum, albeit phrased differently. In addition, do a search and read through the countless threads on the topic. Disregard anything a pre-medical student says, especially in the pre-allo forums. They know absolutely nothing about career options as a DO aside from what they read here and re-word.
For the average medical student wanting to do private practice or a standard hospital gig, there's not a meaningful difference. As noted above, there is a big disproportion when you're looking at academic programs and competitive ACGME residencies. There are also an incredibly low proportion of MD students landing these spots so it's not like if you show up at an average MD school and graduate you're going to land ortho at Pitt (the door is at least present and open though). However, there are AOA residencies in those specialties and I think it is only fair to note that. You can be an ortho surgeon as a DO you just won't be ACGME trained, but that is a moot point after the accreditation merger (tier/prestige will still matter for some jobs/fellowships).
In reality the a below average NYU student can easily land a mid-tier university IM residency in a desirable location for example while a similar below average DO student would end up at some tiny community program
This is also worth noting. If you're a top DO student you can land ACGME university programs in most specialties and AOA programs in the surgical subspecialties. Being a below average DO student would be incredibly frightening if you wanted to do something other than primary care, become a surgeon, or have a research career.
Regarding research, it is very possible to do research as a DO medical student and resident. I am publishing 5 papers in 2014, more than most MD students at top programs. However, I would never be granted a residency position or job at the places I do that research at (fellowship possibly). I'm talking zero precent chance. It is something to consider if you absolutely want to be in academia. It is very, very important to realize that academic prestige doesn't mean everything if you don't want that career and if you do want to work in a smaller community hospital. Different people want different things and although I am publishing frequently now, I would rather not be a physician than do academic medicine for a career so that variable is of no concern.
I don't always respect meattornados tone and often not his message, but there are some things to legitimately consider and although presented in an antagonistic tone here, are factual. These things should be individually weighted based on career and lifestyle goals. There are excellent education and career options for DO students that put the work in. However, it is important to realistically weigh some limitations which may or may not be important to you.
These conversations are a joke on SDN, do yourself a favor and PM DO students to get accurate responses. Goro is an invaluable resource on this site for many students, especially those applying DO.