# bcc (100) and (200) planes and their xrd peaks

(a) I understand (100) lattice planes with an interplanar spacing of a if we assume it to be a bcc lattice of lattice parameter a. Then (200) planes have an interplanar spacing of a/2 but that would mean that (200) and (100) planes coincide. While the (100) and (200) planes are same if viewed separately, they can be thought of as displaced 0.5y and 0.5z

Then, is it correct to say that we can generate the whole bcc by stacking (200) planes? I saw it in an answer. https://physics.stackexchange.com/a/595819/338776

(b) In Kittel's solid state physics, the physical interpretation of no reflection peaks for (100) is that an intervening plane of atoms between the 100 planes( which i can only assume is the (200) plane) differs in phase with the first plane by an angle π and so cancels the contribution from the first plane. If it is indeed the case, then the same happens for (200) planes as the two planes are equivelant, so why do we see (200) peaks?