However, it cannot replace the real materials.
why is cannot different with can not?
I don't know. Somehow the people who first invented and used the English language decided that we should use "cannot" in writing, and we just follow, nobody knows why. Oh, speaking of "nobody", why is it not "no body"?, I guess we should just follow...
Good news is that you can use "can not" or "no body", and everyone still understand :)
by the way, it's "different from" or "different than", not "different with" :p