True, but even here we're not talking about identical molecules. Chiral molucules are ones (which are usually organic--based on carbon) which have both "left handed" and "right handed" versions. The two versions have the same molecular formula, but they're opposites of each other. So it's like having a left-hand drive car versus a right-hand drive car: they might look identical using a mirror, but they're really not, and you can't use them the same way because the way they interact with their environment is different (a driver in a RHD car in a LHD country will have a hard time seeing everything properly because the roads aren't designed with this configuration in mind).