Originally posted by Fogel70 The difference is that IPX is a standard that they must comply to. With WR and AW they can set whatever conditions they may like as it is their own standard.
AW sealings are probably equivalent of IP45 or better, and WR of IP34 or better, but as they are not fully encapsulated they can not apply this specification on them.
The highest rating they can use is probably the same as Olympus - IPX1, but that is conditions that most cameras or lenses can withstand, sealed or not.
IPX is also a voluntary standard. You might certify in order to win a commercial or government contract, that might ask for an IP34 product. You go for it when you think it's a point of difference with your opposition, and it could be argued Pentax might like to play this up versus the other brands, especially in the entry level products.
Pentaxians frequently cite WR and ruggedness of build as to why they bought their camera in the first place.
In a later post, you acknowledge the rating applies to normal usage, not when changing lenses. So that'd be true also for changing batteries and SD cards.