Telling the difference between illusion and reality is sometimes difficult. Maybe this is because illusion and reality are the same.
Whatever is perceived or thought about is simply an appearance in consciousness. It's all equally real and equally fantastic. Nothing is more or less real than anything else.
There's nothing outside of consciousness, no distinct, 'objective' world to be cataloged and manipulated. The appearance of something in consciousness constitutes its existence, its being, its reality. Consciousness is both the appearance of that something and the awareness of it. These are the same. There's no duality—except within the appearance itself, where everything is different and seen from differing viewpoints.
That's an illusion. But it's also reality, because there isn't anything else.