tramp steamer vs steamship

tramp steamer and steamship both are nouns.

Word	Noun	Adjective	Verb	Adverb
tramp steamer	Yes	No	No	No
steamship	Yes	No	No	No

As nouns, steamship is a hypernym of tramp steamer; that is, steamship is a word with a broader meaning than tramp steamer:

tramp steamer: a commercial steamer for hire; one having no regular schedule
steamship: a ship powered by one or more steam engines

Other hypernyms of tramp steamer include steamer.

tramp steamer (noun)	steamship (noun)
a commercial steamer for hire; one having no regular schedule	a ship powered by one or more steam engines