field of regard vs field of vision

field of regard and field of vision both are nouns.

Word	Noun	Adjective	Verb	Adverb
field of regard	Yes	No	No	No
field of vision	Yes	No	No	No

As nouns, field of regard and field of vision are synonyms defined as:

field of regard and field of vision: all of the points of the physical environment that can be perceived by a stable eye at a given moment

Other synonyms of field of regard include visual field.

field of regard (noun)	field of vision (noun)
all of the points of the physical environment that can be perceived by a stable eye at a given moment	all of the points of the physical environment that can be perceived by a stable eye at a given moment