ditch vs ha-ha

ditch and ha-ha both are nouns.

Word	Noun	Adjective	Verb	Adverb
ditch	Yes	No	Yes	No
ha-ha	Yes	No	No	No

As nouns, ha-ha is a hyponym of ditch; that is, ha-ha is a word with a more specific, narrower meaning than ditch:

ditch: a long narrow excavation in the earth
ha-ha: a ditch with one side being a retaining wall; used to divide lands without defacing the landscape

Other hyponyms of ditch include drainage ditch, irrigation ditch, haw-haw, sunk fence, trench, trench.

ditch (noun)	ha-ha (noun)
a long narrow excavation in the earth	a ditch with one side being a retaining wall; used to divide lands without defacing the landscape
any small natural waterway	a loud laugh that sounds like a horse neighing

ditch (verb)	ha-ha (verb)
crash or crash-land
cut a trench in, as for drainage
make an emergency landing on water
forsake
throw away
sever all ties with, usually unceremoniously or irresponsibly