I think it depends entirely how the school administration handles the 'position' for the school nurse. In my district the certified school nurse falls under the 'teachers contract' so I am part of the union, I am salary, I get all the same holidays/inservice days, open houses, and meetings as the teachers (the meetings are annoying because they NEVER apply to me and more often I am allowed to just do busy work in my office during those times). I receive full health benefits for myself and my family and I receive the same amount of PTO and sick time as the teachers.
I am paid year round (with extra on the days that I come in for that I am not contracted such as the middle of august for a week I come in for last minute kindergarten screenings-I get paid hourly for that since that is not in the other teachers contracts).
The other nurses in the district not hired as certified school nurses are hourly employees and are titled 'health aides', no sick time, no vacation time, paid for when they are here, and no health benefits.