geophagy vs pica

geophagy and pica both are nouns.

Word	Noun	Adjective	Verb	Adverb
geophagy	Yes	No	No	No
pica	Yes	No	No	No

As nouns, pica is a hypernym of geophagy; that is, pica is a word with a broader meaning than geophagy:

geophagy: eating earth, clay, chalk; occurs in some primitive tribes, sometimes in cases of nutritional deficiency or obsessive behavior
pica: an eating disorder, frequent in children, in which non-nutritional objects are eaten persistently

geophagy (noun)	pica (noun)
eating earth, clay, chalk; occurs in some primitive tribes, sometimes in cases of nutritional deficiency or obsessive behavior	a linear unit (1/6 inch) used in printing
	an eating disorder, frequent in children, in which non-nutritional objects are eaten persistently