tears vs sobbing

tears and sobbing both are nouns.

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

As nouns, sobbing is a hyponym of tears; that is, sobbing 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)
sobbing: convulsive gasp made while weeping

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

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