optical fusion vs beholding

optical fusion and beholding both are nouns.

Word	Noun	Adjective	Verb	Adverb
optical fusion	Yes	No	No	No
beholding	Yes	No	No	No

As nouns, beholding is a hypernym of optical fusion; that is, beholding is a word with a broader meaning than optical fusion:

optical fusion: the combining of images from the two eyes to form a single visual percept
beholding: perception by means of the eyes

Other hypernyms of optical fusion include seeing, visual perception.

optical fusion (noun)	beholding (noun)
the combining of images from the two eyes to form a single visual percept	perception by means of the eyes