hexagram vs Mogen David

hexagram and Mogen David both are nouns.

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

As nouns, Mogen David is a hyponym of hexagram; that is, Mogen David is a word with a more specific, narrower meaning than hexagram:

hexagram: a regular polygon formed by extending each of the sides of a regular hexagon to form two equilateral triangles
Mogen David: a six-pointed star formed from two equilateral triangles; an emblem symbolizing Judaism

Other hyponyms of hexagram include Magen David, Shield of David, Solomon's seal, Star of David.

hexagram (noun)	Mogen David (noun)
a regular polygon formed by extending each of the sides of a regular hexagon to form two equilateral triangles	a six-pointed star formed from two equilateral triangles; an emblem symbolizing Judaism