sub-test vs mental testing

sub-test and mental testing both are nouns.

Word	Noun	Adjective	Verb	Adverb
sub-test	Yes	No	No	No
mental testing	Yes	No	No	No

As nouns, mental testing is a hypernym of sub-test; that is, mental testing is a word with a broader meaning than sub-test:

sub-test: one of a battery of related tests
mental testing: any standardized procedure for measuring sensitivity or memory or intelligence or aptitude or personality etc

Other hypernyms of sub-test include mental test, psychometric test, test.

sub-test (noun)	mental testing (noun)
one of a battery of related tests	any standardized procedure for measuring sensitivity or memory or intelligence or aptitude or personality etc