gang plow vs mouldboard plough

gang plow and mouldboard plough both are nouns.

Word	Noun	Adjective	Verb	Adverb
gang plow	Yes	No	No	No
mouldboard plough	Yes	No	No	No

As nouns, mouldboard plough is a hypernym of gang plow; that is, mouldboard plough is a word with a broader meaning than gang plow:

gang plow: a plough having two or more shares, coulters, and mouldboards designed to work simultaneously.
mouldboard plough: plow that has a moldboard

Other hypernyms of gang plow include moldboard plow.

gang plow (noun)	mouldboard plough (noun)
a plough having two or more shares, coulters, and mouldboards designed to work simultaneously.	plow that has a moldboard