comment vs second-guess

comment is a noun but second-guess is not a noun.

Word	Noun	Adjective	Verb	Adverb
comment	Yes	No	Yes	No
second-guess	No	No	Yes	No

As verbs, second-guess is a hyponym of comment; that is, second-guess is a word with a more specific, narrower meaning than comment:

Other hyponyms of comment include disc-jockey, disk-jockey, DJ.

comment (noun)	second-guess (noun)
a statement that expresses a personal opinion or belief or adds information
a written explanation or criticism or illustration that is added to a book or other textual material
a report (often malicious) about the behavior of other people

comment (verb)	second-guess (verb)
make or write a comment on	evaluate or criticize with hindsight
provide interlinear explanations for words or phrases	attempt to anticipate or predict
explain or interpret something