toilet vs flush toilet

toilet and flush toilet both are nouns.

Word	Noun	Adjective	Verb	Adverb
toilet	Yes	No	No	No
flush toilet	Yes	No	No	No

As nouns, flush toilet is a hyponym of toilet; that is, flush toilet is a word with a more specific, narrower meaning than toilet:

toilet: a plumbing fixture for defecation and urination
flush toilet: a toilet that is cleaned of waste by the flow of water through it

Other hyponyms of toilet include flushless toilet, lavatory, potty chair, potty seat.

toilet (noun)	flush toilet (noun)
the act of dressing and preparing yourself	a toilet that is cleaned of waste by the flow of water through it
a room or building equipped with one or more toilets
a plumbing fixture for defecation and urination
misfortune resulting in lost effort or money