torsion angle vs dihedral angle

torsion angle and dihedral angle both are nouns.

Word	Noun	Adjective	Verb	Adverb
torsion angle	Yes	No	No	No
dihedral angle	Yes	No	No	No

As nouns, torsion angle and dihedral angle are synonyms defined as:

torsion angle (noun)	dihedral angle (noun)
the angle between two planes.	the angle between two planes.