a big difference... u should've asked about the relation :) age is the number of years someone has lived or something has existed. gender is the fact of being male or female. u might ask about the difference between gender and sex. so, gender is simply a formal word of sex... gender is more formal.

age would be like "how old are you?".. and gender is like your sex..

Age - the length of life or existence (years old); Gender - comprise of Masculine (Male) and Feminine (Female), it's to classified the classes of two sexes, for eg. the Masculine gender for:- 1) auntie will be uncle; 2) waitress will be waiter; 3) lioness will be lion; and the feminine gender for:- 1) grandfather will be grandmother; 2) king will be queen; 3) fox will vixen;