TP2:  I think the real difference involved status as a "protected class."  'Since January 1, 2008, Oregon has banned discrimination in employment, housing, and public accommodations based on both sexual orientation and gender identity.[10] The protections were added by the Oregon Equality Act, signed into law by Governor Ted Kulongoski on May 9, 2007.[1'  wikepedia

definition of public accomodation: Public accommodations. ... Examples include hotels, motels, restaurants, theaters, and all other public accommodations engaged in interstate commerce; exempted are private clubs without defining the term "private". wikepedia

The bakers provide a public accomodation are are, thereby, subject to the anti-discrimination statutes regarding "sexual orientation."  The KKK has not been granted "protected status" in Oregon and I believe a business could refuse their patronage without violating any ordinances or statutes.  However, like you, I'm not an attorney.  regards, Gary Crum