Form, the first aggregate, is something we grasp at that doesn’t have real inherent existence. We tend to have the deluded view the permanent, but nothing has a permanent nature. Everything is empty if we think in terms of how everything is made up of things and has no inherent nature. Our deluded minds may think that our bodies are permanent, but the truth is that we are all subject to birth, old age, sickness, and death. So, that is why we say there is no difference between form and void.