Sex Gender Fruity Loops

Cereal.  An American staple for kids and adults.  Different colors, shapes, and flavors still excite the minds of the masses for breakfast, lunch, and dinner.  There's another cereal that has been tested, tried, and true to be false in reality.  And that is the supposed war between sex and gender.  What is sex?  What is gender?  Are they the same?  What is this battle about and what does the Bible say about it with authority and finality?