restrictions passcode problem
What is the difference between the passcode I enter to turn the iPhone on and the 'restrictions passcode" I am being asked for when trying to erase all settings and data? the phone has never had any problem accepting my passcode which is 4 numbers and 4 letters. I am unable to erase all data and settings before returning an iPhone to carrier because it keeps rejecting the passcode I use everyday. I also don't know why there is only room for 4 numbers in this spot because the passcode as I know it has numbers and letters. is the restrictions passcode different than the passcode I use every day? I also am certain that I never enable "restrictions" in settings>general>restrictions. This is set to on and I am unable to turn it off. How do I get the data erased before returning the phone? I can't return it until this is done.
iPhone 6 Plus, iOS 8.0.2