towboat vs tugboat

towboat and tugboat both are nouns.

Word	Noun	Adjective	Verb	Adverb
towboat	Yes	No	No	No
tugboat	Yes	No	No	No

As nouns, towboat and tugboat are synonyms defined as:

towboat and tugboat: a powerful small boat designed to pull or push larger ships

Other synonyms of towboat include tower, tug.

towboat (noun)	tugboat (noun)
a powerful small boat designed to pull or push larger ships	a powerful small boat designed to pull or push larger ships