Distinction of esse and essentia

"Esse" refers to the act of being or existence itself—simply that something exists. "Essentia," on the other hand, means the essence or true nature of a thing—the qualities that make something what it fundamentally is. For example, the esse of a tree is its existence as a tree, while its essentia includes its tree-like qualities such as leaves and roots. In philosophy, distinguishing between esse (being) and essentia (whatness) helps us understand not just that something exists, but what makes it what it is.