There are a few differences in working for an academy school. An Academy is a school that is publically funded, they do not have to follow the national curriculum and can set their own term times. Often failing schools are forced to become academies by the government. The school is then often ran by sponsors rather than governors.
Academies do not have to employ qualified teachers to work in their classrooms. Usually schools can only employ teachers that have a QTS (Qualified Teacher Status) qualification but recently the government have changed the rules for academies allowing them to employ people such as computer scientists to teach the pupils.
Academies are allowed to stipulate their own working hours and rates of pay for teachers. If the school you are currently working in gets turned in to an academy you may find that you have to take a pay drop and work longer hours.