seaway vs ship route

seaway and ship route both are nouns.

Word	Noun	Adjective	Verb	Adverb
seaway	Yes	No	No	No
ship route	Yes	No	No	No

As nouns, seaway and ship route are synonyms defined as:

seaway and ship route: a lane at sea that is a regularly used route for vessels

Other synonyms of seaway include sea lane, trade route.

seaway (noun)	ship route (noun)
a lane at sea that is a regularly used route for vessels	a lane at sea that is a regularly used route for vessels