anisogamy vs amphimixis

anisogamy and amphimixis both are nouns.

Word	Noun	Adjective	Verb	Adverb
anisogamy	Yes	No	No	No
amphimixis	Yes	No	No	No

As nouns, amphimixis is a hypernym of anisogamy; that is, amphimixis is a word with a broader meaning than anisogamy:

anisogamy: (biology) reproduction by the union or fusion of two differing gametes (especially differing in size)
amphimixis: reproduction involving the union or fusion of a male and a female gamete

Other hypernyms of anisogamy include sexual reproduction.

anisogamy (noun)	amphimixis (noun)
(biology) reproduction by the union or fusion of two differing gametes (especially differing in size)	union of sperm and egg in sexual reproduction
	reproduction involving the union or fusion of a male and a female gamete