They are both Oxycodone, but
Percocet is the faster acting instant release
medicine which also contains tylenol, and is typically taken every 4-6 hours, OR as needed for breakthrough pain when used in conjunction with an extended release med. Oxycontin is the long lasting extended relief form of oxycodone that does not contain tylenol, and is typically taken every 12 hours.
So you are coming off of them now? Are you weaning yourself off them?