According to Osho, fullness and emptiness name the same ultimate experience from different angles: when the miseries, anxieties and falsities of the world disappear, it looks like nothingness; what remains is felt as fullness—bliss, light, presence, essential reality. It is empty of the world and ego, yet full of God/being. Buddha preferred the term emptiness to prevent the ego from turning fullness into a goal.
They’re the same thing: when all the fake, heavy stuff drops away it seems empty, but what’s left is a quiet, shining fullness.