Prussian Blue analogues are widely investigated as positive electrode materials for sodium-ion batteries; among those, FeFe and FeMn based materials are particularly interesting, and several chemical suppliers have recently begun offering commercial-grade materials. Here, we perform a comprehensive structural, spectroscopic, and electrochemical comparison of two commercially available MnFe–PW (Prussian White) samples and one FeFe–PB (Prussian Blue) analogue. Despite nominal compositional similarity, the MnFe–PW samples show markedly different electrochemical behavior when tested in high loading electrodes, which aligns with differences in microstructure and impurity levels. Operando synchrotron Fourier-transform infrared and operando x-ray diffraction have been performed to gain further insight on the fate of water molecules during cell operation, which was found to be significantly different for MnFe–PW and FeFe–PB.