Not sure what this has to do with Open Carry....but...
The difference is that we are in Washington. The Washington Constitution Article 1 section 7 reads: "SECTION 7 INVASION OF PRIVATE AFFAIRS OR HOME PROHIBITED. No person shall be disturbed in his private affairs, or his home invaded, without authority of law."
This is significantly different than the Federal 4th amendment, which states "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
Some crucial differences are "disturbed" vs "unreasonable searches and seizures"; "private affairs" vs "persons, houses, papers and effects". The framers of the Washington Constitution were concerned that the rapid pace of technological advance at the time might render "papers and effects" moot, as the US Congress was attempting to limit those protections. As well they choose "disturbed" as there were efforts in the US Congress to widen what was "reasonable" - such as Congress demanding private businesses turn over business papers.
A good case showing the distinction in action comes from education law. In New Jersey v T.L.O. the U.S. Supreme Court said that school officials may search a student or a student’s property without a warrant and without probable cause. The Court ruled that students are under the authority of school administrators and simply must be reasonable. In Washington State the State Supreme Court held that school administrators are public officials and that children were not voluntarily under their authority. Therefore Washington holds searches to a higher standard than the US Supreme Court. In Washington schools must have “individualized reasonable suspicion.” The school exemption for warrants: "Teachers and administrators have a substantial interest in maintaining discipline in the classroom and on school grounds that often requires swift action“ – State v McKinnon (1977).