sex character vs sex characteristic

sex character and sex characteristic both are nouns.

Word	Noun	Adjective	Verb	Adverb
sex character	Yes	No	No	No
sex characteristic	Yes	No	No	No

As nouns, sex character and sex characteristic are synonyms defined as:

sex character and sex characteristic: those characteristics (both anatomical and psychological) that are strongly associated with one sex relative to the other

Other synonyms of sex character include sexual characteristic.

sex character (noun)	sex characteristic (noun)
those characteristics (both anatomical and psychological) that are strongly associated with one sex relative to the other	those characteristics (both anatomical and psychological) that are strongly associated with one sex relative to the other