I've only ever used an UNO and was consider getting a mega or due to play around with. Are these two different kinds of programming language? Will the codes I wrote for my uno work the same on these? Or can someone point me into the direction of explanations on the differences. (I know the due is 3.3v but I'm more concerned with the programming.)
Will the codes I wrote for my uno work the same on these?
Going to the Mega2560 will be easier, but may require changes if you have used libraries that use low-level chip features. Arduino code you write is very compatible from the UNO up the technology line, but you may need to make minimal changed.
Moving to the Due will depends, again, on libraries you use. Code written in the GUI editor will generally work and conflicts are documented if you go looking.