i'm thinking you've already had your questioned answered by now but just in case..
drew/ucla is different from prime. prime is a 5 year program where students get their masters in something that will aid them in their future work with underserved communities. drew/ucla is a program that also focuses on working with the underserved, however students are not required to do a masters. the first two years are at ucla and then the 24 students do their rotations at king and other ucla affiliated hospitals. drew/ucla students are also required to do a research thesis during the program.