sociology vs psephology

sociology and psephology both are nouns.

Word	Noun	Adjective	Verb	Adverb
sociology	Yes	No	No	No
psephology	Yes	No	No	No

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

sociology: the study and classification of human societies
psephology: the branch of sociology that studies election trends (as by opinion polls)

Other hyponyms of sociology include criminology, demography, human ecology, sociometry, psychographics.

sociology (noun)	psephology (noun)
the study and classification of human societies	the branch of sociology that studies election trends (as by opinion polls)