According to Osho, the judge is your socially conditioned conscience that constantly labels experiences as good or bad, right or wrong - an inner policeman differing across cultures. The witness is pure awareness: mirrorlike, non-evaluative seeing of thoughts, feelings, and events. Cultivating witnessing frees you from imposed ideologies and guilt, aligning you with a universal consciousness shared by awakened ones, while dismantling the inner judge's dominance.
The judge is the learned voice saying good or bad; the witness is you just watching quietly without taking sides.