The microscopic origin of high carrier mobility in transition‑metal diphosphides remains under debate, with proposed mechanisms including hydrodynamic electron flow and suppressed momentum relaxation associated with spin‑momentum locking. α‑WP₂ provides a useful platform for addressing this issue because it crystallizes in two polymorphs: monoclinic α‑WP₂, a topologically trivial semimetal, and orthorhombic β‑WP₂, a type‑II Weyl semimetal. Here, we grew high‑quality α‑ and β‑WP₂ single crystals with residual‑resistivity ratios of 3700 and 4200, respectively. Electrical transport measurements yield carrier mobilities of 1.90×10⁵ and 1.88×10⁵ cm² V⁻¹ s⁻¹ at 5 K for α‑ and β‑WP₂, corresponding to transport lifetimes τₜ of 6.93×10⁻¹¹ and 1.38×10⁻¹⁰ s. Low‑temperature resistivity analysis shows that the data are better described by residual impurity scattering together with a phonon‑drag‑related contribution than by simple T² electron‑electron or T⁵ electron‑phonon forms. Raman spectra show linewidth broadening and weak Fano‑like asymmetry in selected phonon modes, indicating mode‑dependent electron‑phonon coupling. Analysis of the electronic Raman response gives quantum quasiparticle lifetimes τq of 4.25×10⁻¹⁴ and 3.74×10⁻¹⁴ s at 5 K for α‑ and β‑WP₂, yielding τₜ/τq = 1632 and 3698, respectively. To account for this large τₜ/τq, we propose that two mechanisms may play crucial roles: spin‑orbit coupling (SOC), which suppresses backscattering for k‑points near band extrema, and orbital‑momentum locking (OML), which restrains large‑angle scattering for k‑points away from band extrema. These results provide a comparative view of carrier scattering in the two phases of WP₂ and suggest that SOC and OML are relevant to the high mobility in transition‑metal diphosphides.