tears vs sob

tears and sob both are nouns.

Word	Noun	Adjective	Verb	Adverb
tears	Yes	No	No	No
sob	Yes	No	Yes	No

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

tears: the process of shedding tears (usually accompanied by sobs or other inarticulate sounds)
sob: convulsive gasp made while weeping

Other hyponyms of tears include snivel, sniveling, sobbing, bawling, wailing.

tears (noun)	sob (noun)
the process of shedding tears (usually accompanied by sobs or other inarticulate sounds)	convulsive gasp made while weeping

tears (verb)	sob (verb)
	weep convulsively