Your WDFW pass works at all area's controlled by Washington Department of Fish and Wildlife.  Which include nearly a million acres of land divided into 32 designated Wildlife Areas across the state. More than 150 Water Access Sites owned or maintained by WDFW provide boating access to lakes, rivers and marine areas in or near state Wildlife Areas.

To use State Parks and other lands controlled by the state, you must have the Discover Pass.  Which include nearly 7 million acres of Washington state-managed recreation lands – including state parks, water-access points, heritage sites, wildlife and natural areas, trails and trailheads.

Bottom line is.....if you only have the WDFW pass you are limited to just WDFW controlled lands.  If you have the Discover Pass....you can access not only State Parks and  DNR lands but also WDFW land.