Originally Posted by noahath

Oh boy:

Some defiitions for you:
Gender (gender - Definitions from Dictionary.com)

(in many languages) a set of classes that together include all nouns, membership in a particular class being shown by the form of the noun itself or by the form or choice of words that modify, replace, or otherwise refer to the noun, as, in English, the choice of he to replace the man, of she to replace the woman, of it to replace the table, of it or she to replace the ship. The number of genders in different languages varies from 2 to more than 20; often the classification correlates in part with sex or animateness. The most familiar sets of genders are of three classes (as masculine, feminine, and neuter in Latin and German) or of two (as common and neuter in Dutch, or masculine and feminine in French and Spanish).

Sex (sex - Definitions from Dictionary.com)
either the male or female division of a species, esp. as differentiated with reference to the reproductive functions.

Sex is the physical identifier; gender is the personal identifier or action of either demonstrating or representing "masculine" vs "feminine".