gable vs pediment

gable and pediment both are nouns.

Word	Noun	Adjective	Verb	Adverb
gable	Yes	No	No	No
pediment	Yes	No	No	No

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

gable: the vertical triangular wall between the sloping ends of gable roof
pediment: a triangular gable between a horizontal entablature and a sloping roof

Other hyponyms of gable include bell gable, corbie gable.

gable (noun)	pediment (noun)
the vertical triangular wall between the sloping ends of gable roof	a triangular gable between a horizontal entablature and a sloping roof