What kinds of things do research heavy schools ask about research experience?
At research heavy schools, there's a good chance your faculty interviewer will be a researcher of some sort and so they'll ask you basic questions about your research:
"Tell me about your research project" (maybe "Explain it to me like I'm a 5th grader").
The goal of this question is usually to (a) make sure that you know what you were doing and (b) see if you can explain a complex topic in a simple manner that a stranger can understand. I think often times people will sacrifice (b) for (a) and often their interviewer will just get this glazed look on their face and will just wait to ask the next question.
They might also ask things like, "What role did you have in this research project?" and "What did you learn from this research project?"
Also, what does it matter whether you go to a research heavy school vs a primary care oriented school? Do you get to do research while in med school? What is so significant about this difference in med school orientation?
If you want to do research, it will (presumably) be easier to find research projects at a research heavy school. They might have funding programs in place for students, they might have programs and pipelines set up so that finding research is easier, they might have a lot more faculty/labs that are eager for medical students to help them with various projects, etc.
Some competitive specialties look for research in their applicants, and doing research in that field in med school can be an advantage.
Do you get taught differently?
No. All schools are pretty much required to teach the same material
Sometimes at a research heavy school you might have lecturers be more likely to go off on random tangents about some research that they are really interested in but will never be tested on the boards or relevant in your clinical career.
Also, during the interviews, do they ask you for extensive details about what you researched during undergrad if you do have good research experience?
I think it really depends on your interviewer. I had some pretty extensive research experience and some interviewers asked me for some details just because they were curious about stuff I had said, but it's not like they had read the publications and were grilling me about it.
I also think the LOR that you get from your research advisor will tell them a lot. If you contributed a great deal and the advisor writes something like, "This student contributed a level of work that I see from senior graduate students in my lab," they're not really going to doubt you as much as if the professor writes "This student showed up on time and was interested in the material."