[nevcairiel]

DTS core, like most lossy codecs, do not have an actual bitdepth. The difference here is that the header contains a flag called "original bitdepth", which some decoders use to decide on how to output the audio. If its 24-bit, there is a chance you might get a bit more precision.
Other decoders ignore this flag entirely and always output 16-bit, or always output floating point.

In summary, its really not a huge difference, it doesn't change the audio, just a bit in the header. Overall the "24-bit version" is probably slightly better.