specter vs phantasm

specter and phantasm both are nouns.

Word	Noun	Adjective	Verb	Adverb
specter	Yes	No	No	No
phantasm	Yes	No	No	No

As nouns, phantasm is a hypernym of specter; that is, phantasm is a word with a broader meaning than specter:

Other hypernyms of specter include apparition, fantasm, phantasma, phantom, shadow.

As nouns, specter and phantasm are synonyms defined as:

Other synonyms of specter include apparition, fantasm, phantasma, phantom, spectre.

specter (noun)	phantasm (noun)
a mental representation of some haunting experience	something existing in perception only
a ghostly appearing figure	a ghostly appearing figure