rowboat vs rowing boat

rowboat and rowing boat both are nouns.

Word	Noun	Adjective	Verb	Adverb
rowboat	Yes	No	No	No
rowing boat	Yes	No	No	No

As nouns, rowing boat is a hyponym of rowboat; that is, rowing boat is a word with a more specific, narrower meaning than rowboat:

rowboat: a small boat of shallow draft with cross thwarts for seats and rowlocks for oars with which it is propelled
rowing boat: a rowboat

Other hyponyms of rowboat include wherry.

rowboat (noun)	rowing boat (noun)
a small boat of shallow draft with cross thwarts for seats and rowlocks for oars with which it is propelled	a rowboat