pica vs geophagia

pica and geophagia both are nouns.

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

As nouns, geophagia is a hyponym of pica; that is, geophagia is a word with a more specific, narrower meaning than pica:

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

Other hyponyms of pica include geophagy.

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