containership vs container ship

containership and container ship both are nouns.

Word	Noun	Adjective	Verb	Adverb
containership	Yes	No	No	No
container ship	Yes	No	No	No

As nouns, containership and container ship are synonyms defined as:

containership and container ship: a cargo ship designed to hold containerized cargoes

Other synonyms of containership include container vessel.

containership (noun)	container ship (noun)
a cargo ship designed to hold containerized cargoes	a cargo ship designed to hold containerized cargoes