Mogen David vs allegory

Mogen David and allegory both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mogen David	Yes	No	No	No
allegory	Yes	No	No	No

As nouns, allegory is a hypernym of Mogen David; that is, allegory is a word with a broader meaning than Mogen David:

Mogen David: a six-pointed star formed from two equilateral triangles; an emblem symbolizing Judaism
allegory: a visible symbol representing an abstract idea

Other hypernyms of Mogen David include emblem, hexagram.

Mogen David (noun)	allegory (noun)
a six-pointed star formed from two equilateral triangles; an emblem symbolizing Judaism	a short moral story (often with animal characters)
	an expressive style that uses fictional characters and events to describe some subject by suggestive resemblances; an extended metaphor
	a visible symbol representing an abstract idea