mental strain vs nervous strain

mental strain and nervous strain both are nouns.

Word	Noun	Adjective	Verb	Adverb
mental strain	Yes	No	No	No
nervous strain	Yes	No	No	No

As nouns, mental strain and nervous strain are synonyms defined as:

mental strain and nervous strain: (psychology) nervousness resulting from mental stress

Other synonyms of mental strain include strain.

mental strain (noun)	nervous strain (noun)
(psychology) nervousness resulting from mental stress	(psychology) nervousness resulting from mental stress