Yes the engines are different - not just adding a turbo so to speak - biggest difference is compression ratio and pistons from a block or short motor point of view - high compression in N/A and lower compression in Turbo engine.
There are various other differences including cam shafts with different timing, knock sensors, oil pans, coolant/oil pipes, gearbox, etc.
There are various threads on the forum about the differences as this question has been asked by various people.
I guess in theory the blocks could be swapped and all the ancillaries/cylinder head, etc be changed over but the difference in compression of the pistons would still be the big issue requiring modification. But that would defeat the purpose of what you are trying to do....