heartbreak vs dolour

heartbreak and dolour both are nouns.

Word	Noun	Adjective	Verb	Adverb
heartbreak	Yes	No	No	No
dolour	Yes	No	No	No

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

heartbreak: intense sorrow caused by loss of a loved one (especially by death)
dolour: (poetry) painful grief

Other hyponyms of heartbreak include dolor.

heartbreak (noun)	dolour (noun)
intense sorrow caused by loss of a loved one (especially by death)	(poetry) painful grief