They are considered separate programs and, I believe at some schools it is a separate AMCAS entry. AMCAS only allows you to apply to one program at a school. However, some of the schools may have option to indicate PRIME on secondary so you can apply to both
As for being a candidate, it is hard enough to get into any med school. For a PRIME you better have several hundred hours of evidence showing commitment to underserved populations as well as leadership. Also, you do not want to stuck in a program that is destined for primary care and then want to change to another specialty. While a school cant stop you from doing do, they can refuse to write you supporting letters for residency which could kill your chances at a slot. So you better be damn sure this is where you want to go