gangway vs gangplank

gangway and gangplank both are nouns.

Word	Noun	Adjective	Verb	Adverb
gangway	Yes	No	No	No
gangplank	Yes	No	No	No

As nouns, gangway and gangplank are synonyms defined as:

gangway and gangplank: a temporary bridge for getting on and off a vessel at dockside

Other synonyms of gangway include gangboard.

gangway (noun)	gangplank (noun)
a temporary passageway of planks (as over mud on a building site)	a temporary bridge for getting on and off a vessel at dockside
a temporary bridge for getting on and off a vessel at dockside
passageway between seating areas as in an auditorium or passenger vehicle or between areas of shelves of goods as in stores