Flying Dutchman vs fantasm

Flying Dutchman and fantasm both are nouns.

Word	Noun	Adjective	Verb	Adverb
Flying Dutchman	Yes	No	No	No
fantasm	Yes	No	No	No

As nouns, fantasm is a hypernym of Flying Dutchman; that is, fantasm is a word with a broader meaning than Flying Dutchman:

Flying Dutchman: a phantom ship that is said to appear in storms near the Cape of Good Hope
fantasm: something existing in perception only

Other hypernyms of Flying Dutchman include apparition, phantasm, phantasma, phantom, shadow.

As nouns, fantasm is a hypernym of Flying Dutchman; that is, fantasm is a word with a broader meaning than Flying Dutchman:

Flying Dutchman: the captain of a phantom ship (the Flying Dutchman) who was condemned to sail against the wind until Judgment Day
fantasm: a ghostly appearing figure

Other hypernyms of Flying Dutchman include apparition, phantasm, phantasma, phantom, specter, spectre.

Flying Dutchman (noun)	fantasm (noun)
a phantom ship that is said to appear in storms near the Cape of Good Hope	something existing in perception only
the captain of a phantom ship (the Flying Dutchman) who was condemned to sail against the wind until Judgment Day	a ghostly appearing figure