AN AP is the short cut to saying ANNUAL PASS.......if you plan on going to Disney more then once during a year then this is very nice to have and is sometimes cheaper. ALSO with an annual pass you can purchase the DDE card which gives AP's twenty percent off their food and beverages at certain restaurants and also in some resorts.........hope this helps..
ALso an AP rate is a discount that is given to the holders for their hotels at a certain time of the year