There could easily be terminology confusion here.
The subframe bushings are those that mount the subframe to the body. The differential sub frame bushings, mount the differential to the subframe.
The subframe bushings are no big deal. The differential subframe bushings require the puller, or as suggested, air chisel them out. If you air chisel them out, you will still need the puller to install them without destroying the sheet metal subframe.
Have a great day,