I am one of those "chaps" in the HeadFi discussion.
Helpful Vocab guide:
PCM = PCM
DM = PWM = (1-bit) DPCM
SDM = PDM = DSD
As a technology, Sigma-Delta Modulation is more advanced than Delta Modulation. The Sharp uses Sigma-Delta Modulation, while the TI's are Delta Modulation. However, it seems as if TI's execution of DM is more refined than Sharp's execution of SDM.