The best way to explain the hybrid primary is by examining the ballots that voters may choose to use. Shown below are “mock” ballots for the 2016 U.S. Presidential Primary. These are representations of actual ballots received by Oregon voters in May of 2016. (Note: Oregon had 3 major parties in 2016, but the third party had no presidential candidate.)
A closed primary is a private election, limited to affiliated party members, who must declare their party affiliation in order to participate. All unaffiliated voters are excluded. All unaffiliated candidates are excluded.