trough vs cullis

trough and cullis both are nouns.

Word	Noun	Adjective	Verb	Adverb
trough	Yes	No	No	No
cullis	Yes	No	No	No

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

trough: a channel along the eaves or on the roof; collects and carries away rainwater
cullis: a gutter in a roof

Other hyponyms of trough include chute, slide, slideway, sloping trough.

trough (noun)	cullis (noun)
a channel along the eaves or on the roof; collects and carries away rainwater	a gutter in a roof
a container (usually in a barn or stable) from which cattle or horses feed
a long narrow shallow receptacle
a narrow depression (as in the earth or between ocean waves or in the ocean bed)
a treasury for government funds
a concave shape with an open top