College Football Help?

ok so i asked this before i want to know what are those numbers next to college football team names. i know thats theres an AP standing or something like that. whats the diffrenece between those like AP and CP or whatever the other ranking systems are called and are that bcs standings a whole diffrenet standings or what !? this is my first year in college football and it is some confusing sH*t so i would appreciate all the help i can get thanks !