fantasy vs bubble

fantasy and bubble both are nouns.

Word	Noun	Adjective	Verb	Adverb
fantasy	Yes	No	Yes	No
bubble	Yes	No	Yes	No

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

Other hyponyms of fantasy include ignis fatuus, will-o'-the-wisp, wishful thinking.

fantasy (noun)	bubble (noun)
imagination unrestricted by reality	a dome-shaped covering made of transparent glass or plastic
something many people believe that is false	an impracticable and illusory idea
fiction with a large amount of imagination in it	a speculative scheme that depends on unstable factors that the planner cannot control
	a hollow globule of gas (e.g., air or carbon dioxide)

fantasy (verb)	bubble (verb)
indulge in fantasies	expel gas from the stomach
	form, produce, or emit bubbles
	cause to form bubbles
	rise in bubbles or as if in bubbles
	flow in an irregular current with a bubbling noise