cleistogamy vs self-pollination

cleistogamy and self-pollination both are nouns.

Word	Noun	Adjective	Verb	Adverb
cleistogamy	Yes	No	No	No
self-pollination	Yes	No	No	No

As nouns, self-pollination is a hypernym of cleistogamy; that is, self-pollination is a word with a broader meaning than cleistogamy:

cleistogamy: the production of small nonopening self-pollinating flowers
self-pollination: fertilization by transfer of pollen from the anthers to the stigma of the same flower

cleistogamy (noun)	self-pollination (noun)
the production of small nonopening self-pollinating flowers	fertilization by transfer of pollen from the anthers to the stigma of the same flower