Flying Dutchman vs specter

Flying Dutchman and specter both are nouns.

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

As nouns, specter is a hypernym of Flying Dutchman; that is, specter 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
specter: a ghostly appearing figure

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

Flying Dutchman (noun)	specter (noun)
a phantom ship that is said to appear in storms near the Cape of Good Hope	a mental representation of some haunting experience
the captain of a phantom ship (the Flying Dutchman) who was condemned to sail against the wind until Judgment Day	a ghostly appearing figure