Streaming differences between ALAC and FLAC?

Hi, why can FLAC be streamed up to 24-bit/192kHz but Apple Lossless to 24-bit/96kHz? Is this a limitation of the Codec or the hardware? My music collection is ripped from from CD to ALAC but I am starting to build a collection of Studio Masters and ideally would like to manage everything through iTunes (if possible :-) ).

Any advice or guidance is appreciated?

Thanks Simon