Is my red the same as your red?

Nobody can pass you their red to compare, so the answer depends on how each experience is organized. OPH identifies experience with certain organized processes in which an observer reads its own state for its own repair, a commitment it adds on top of its definition of an observer. On that identity the character of red is its place in that organization, meaning which colors it sits close to or apart from and what it leads the observer to expect and do. Where two people's readings line up in all those relations, their reds are alike in character, and each person still has their own. A swapped spectrum that left every relation in place would change nothing, because the organization is the character and nothing is left over to swap. Real differences exist, as color blindness shows, and they appear as differences in which colors a person can tell apart. Which brain cells carry those distinctions is a question for experiment.

Also in Chapter 11: What Does Everybody Actually End Up Holding?.