incidence angle vs angle of incidence

incidence angle and angle of incidence both are nouns.

Word	Noun	Adjective	Verb	Adverb
incidence angle	Yes	No	No	No
angle of incidence	Yes	No	No	No

As nouns, incidence angle and angle of incidence are synonyms defined as:

incidence angle and angle of incidence: the angle that a line makes with a line perpendicular to the surface at the point of incidence

incidence angle (noun)	angle of incidence (noun)
the angle that a line makes with a line perpendicular to the surface at the point of incidence	the angle that a line makes with a line perpendicular to the surface at the point of incidence