The two sets are the following: $(0,1) $ and $ [0,1]$
I know that (the cardinality of) $|(0,1)|=| \mathbb R|$ so it has to be true, that $[0,1]=| \mathbb R |$
Can I maybe use Hilbert's paradox of the Grand Hotel, or should I found a function, which Domain is $(0,1)$?