fellowship pay depends on who the sponsor (funder) of the fellowship is, and the institutional commitment (i.e. does the institution kick in any money or is it grants) to the fellowship.
here at columbia presbyterian, up until a couple of years ago, fellows were hired by columbia university (not presbyterian hospital) so they were only getting paid 30K or so (less than PGY-1; residents are hospital employees here) and had no benefits other than departmentally paid health insurance for self (not family). a few years ago, the fellowships were transferred to newyork-presbyterian hospital and now they get paid on the hospital's PGY scale, with a cut occurring at the pgy-7 level. they are entitled to full hospital employee benefits as well.
i did a faculty development fellowship which was administered by columbia university which was funded on a federal grant, so i would have only gotten paid $30K or so, but the hospital kicked in a portion of my salary in exchange for clinical time and that brought me up to the appropriate pgy4 and pgy5 level.
so it all depends on where the source of funding comes from, and what the local insitutional rules are.