Grandmaternal is a hyponym of grandparental.
As adjectives the difference between grandmaternal and grandparental
is that grandmaternal
is of or relating to a grandmother while grandparental
is of or relating to a grandparent.
of or relating to a grandmother
of or relating to a grandparent
enate (maternal grandparents only)
*(grandfather) grandfatherly, grandpaternal
*(grandmother) grandmaternal, grandmotherly