croak vs suffocate

croak is a noun but suffocate is not a noun.

Word	Noun	Adjective	Verb	Adverb
croak	Yes	No	Yes	No
suffocate	No	No	Yes	No

As verbs, suffocate is a hyponym of croak; that is, suffocate is a word with a more specific, narrower meaning than croak:

croak: pass from physical life and lose all bodily attributes and functions necessary to sustain life
suffocate: be asphyxiated; die from lack of oxygen

Other hyponyms of croak include abort, asphyxiate, stifle, buy it, pip out, drown, predecease, famish, starve, fall, succumb, yield.

croak (noun)	suffocate (noun)
a harsh hoarse utterance (as of a frog)

croak (verb)	suffocate (verb)
pass from physical life and lose all bodily attributes and functions necessary to sustain life	struggle for breath; have insufficient oxygen intake
make complaining remarks or noises under one's breath	feel uncomfortable for lack of fresh air
utter a hoarse sound, like a raven	be asphyxiated; die from lack of oxygen
	suppress the development, creativity, or imagination of
	become stultified, suppressed, or stifled
	deprive of oxygen and prevent from breathing
	impair the respiration of or obstruct the air passage of