Sartre’s Being and Nothingness: “Negatite” and “The Lack” what’s the difference?

Sartre describes the existence of Negatites, beings whose structure are defined by our conscious negation. Pierre, our good friend, is nowhere to be found in the caffe. It is our conscious negation of his existence that structures the existence of Pierre’s absense and his remaining nothingness. This is a negatite

Sartre’s describes the existence of “the lack” in which a being is structured from our conscious understanding of this being “lacking something”, like how a crescent moon is defined by its lack of the rest of the moon that we expect.

How are these not the same? It seems to me that Pierre’s absence can be just as understood as our conscious understanding of lacking Pierre, and that the moon’s crescent can be defined by our conscious negation of the moon.