This was a big question I had as well! I just got accepted to Wash U and will begin school next fall.
As far as I can tell, I guess the emphasis of the program (whether it be research or clinical) may vary. This variance may help you find a school that aligns with your long-term goals.
Research-based schools would be programs that not only conduct empirical research within the field, but encourage students to get involved-- one way or another. A clinical-based school is supposedly more focused on what matters to the majority of people going into OT-- becoming an OT and having experience in the field. The important thing to remember is that most schools incorporate both into their curriculum.
If you think of a chemist, there are those who conduct research, publish papers, etc. , work in academia, and probably have a higher level of education or training suited to research. Then, there are also those who do "real" or "applied" chemistry and work in more industrial places. I think any area of science (including OT) works this way. There are researchers and there are practitioners. There are OTs that work in academia or research or hospitals or schools, etc. etc. etc.
However, the cool thing about OT is that you can be and do both! I don't mean to talk up the school I am going to; I am just very excited! If you look on Washington University's website, they have a clinical AND a research track for both MSOT and OTD students. But even if you choose one track, you still have the opportunity to participate and gain skills in the other area. Many of the OTs I shadowed seemed to be very wary of schools that place too much emphasis on research. They were concerned that students missed out on important hands-on experiences outside the classroom (or lab). But I know for me, I would like to be involved in research and perhaps return to academia. This wasn't their path, so I can understand how a research program might seem like a waste of time. (And honestly, if the schools have comparative NBCOT pass rates, retention rates, and placement rates, I don't know how big of a difference it makes.)
I would begin by asking programs that you are interested in about their opportunities for students to get involved in research. You can also ask about clinical site placement, and look at their curriculum to see how much time you will be spending in Fieldwork.
I toured a school with a small-ish average cohort size (30 students). When I asked the person giving a tour (granted, he was not a faculty member nor a student) about research, he did not really have an answer beyond "well, I am sure that students who go through our program will have all the skills they need to do everything required in the field." I did not find this to be a satisfactory answer, so I ended up emailing some faculty about their research. It is important to contact the people you will realistically be interacting with who are in the field-- sometimes admissions people don't have the best or most accurate answers.
OKKKKK--- If any current students or OTs could back me up or correct any misinformation, that'd be great.
I hope you find a school that is a great fit!