CP+ 2015: Ricoh gets serious with new Pentax full-frame zooms

As Smitty1 says, AW is much better than WR. A 2013 lens catalogue described these as:

AW lenses provide maximum weather-resistant and dustproof performance preventing the intrusion of drizzle and dust into the lens barrel.

The next category of “all weather” PENTAX lenses is designated as WR or weather-resistant. These affordable lenses utilize a simplified weather-resistant construction, making it more difficult for water to enter the lens and are designed to repel a light splash of water.

Source Article from http://www.dpreview.com/articles/0551230049/cp-2015-ricoh-gets-serious-with-new-pentax-full-frame-zooms