As adjectives the difference between rapacious and glutton
is that
rapacious is voracious; avaricious while
glutton is gluttonous; greedy; gormandizing.
As a noun glutton is
one who eats voraciously, obsessively, or to excess; a gormandizer.
As a verb glutton is
(archaic) to glut; to satisfy (especially an appetite) by filling to capacity.