Also, another indication the differences between the pads using the numbers painted/stamped onto the backing plates:
H stamped on them in white equals the A/S or Comfort pads.
S stamped on them is the performance pad option.
Also, the coefficient of friction rating of the pads is within the friction code listed on each set of pads. The breakdown of the alphanumeric part number is PA = manufacturer, 4645-2 is the pad formulation code, GG is the coefficient of friction range the pad is formulated to in low temp friction performance and high temp friction performance(GG = .45 to .55 CoF) and A15 is the environmental compliance code A(does not contain cadmium, lead, asbestos, chromium or mercury) and the year of manufacture 2015.
H and S pads are made by different manufacturers, with different compound designations, use the same friction coefficient ranges(GG for both which equals high/low temp friction performance of at least .45mu up to .55mu) and with different environmental impacts. The H pads are more environmentally friendly than the S pads.