onomancy vs fortune telling

onomancy and fortune telling both are nouns.

Word	Noun	Adjective	Verb	Adverb
onomancy	Yes	No	No	No
fortune telling	Yes	No	No	No

As nouns, fortune telling is a hypernym of onomancy; that is, fortune telling is a word with a broader meaning than onomancy:

onomancy: divination by the letters of a name
fortune telling: the art or gift of prophecy (or the pretense of prophecy) by supernatural means

Other hypernyms of onomancy include divination, foretelling, soothsaying.

onomancy (noun)	fortune telling (noun)
divination by the letters of a name	the art or gift of prophecy (or the pretense of prophecy) by supernatural means