truth vs home truth

truth and home truth both are nouns.

Word	Noun	Adjective	Verb	Adverb
truth	Yes	No	No	No
home truth	Yes	No	No	No

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

truth: a fact that has been verified
home truth: an important truth that is unpleasant to acknowledge (as about yourself)

Other hyponyms of truth include verity.

truth (noun)	home truth (noun)
the quality of being near to the true value	an important truth that is unpleasant to acknowledge (as about yourself)
a fact that has been verified
a true statement
conformity to reality or actuality