tugboat vs towboat

tugboat and towboat both are nouns.

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

As nouns, tugboat and towboat are synonyms defined as:

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

Other synonyms of tugboat include tower, tug.

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