  We study the characteristics of the low mass ppbar enhancements near
threshold in the three-body decays B+ to p pbar K+ and B+ to p pbar pi+. We
observe that the proton polar angle distributions in the ppbar helicity frame
in the two decays have the opposite polarity, and measure the forward-backward
asymmetries as a function of the ppbar mass for the p pbar K+ mode. We also
search for the intermediate two-body decays, B+ to pbar Delta++ and B+ to p
Delta0bar, and set upper limits on their branching fractions. These results are
obtained from a 414 fb^{-1} data sample that contains 449 times 10^6 BBbar
events collected near the Upsilon(4S) resonance with the Belle detector at the
KEKB asymmetric-energy e+ e- collider.
