fertilized egg vs beast

fertilized egg and beast both are nouns.

Word	Noun	Adjective	Verb	Adverb
fertilized egg	Yes	No	No	No
beast	Yes	No	No	No

As nouns, beast is a hypernym of fertilized egg; that is, beast is a word with a broader meaning than fertilized egg:

fertilized egg: an animal organism in the early stages of growth and differentiation that in higher forms merge into fetal stages but in lower forms terminate in commencement of larval life
beast: a living organism characterized by voluntary movement

Other hypernyms of fertilized egg include animal, animate being, brute, creature, fauna.

fertilized egg (noun)	beast (noun)
an animal organism in the early stages of growth and differentiation that in higher forms merge into fetal stages but in lower forms terminate in commencement of larval life	a living organism characterized by voluntary movement
	a cruelly rapacious person