Gravitational binding energy and mass defect are related concepts but not exactly the same thing.
Gravitational binding energy refers to the energy required to completely disassemble an object or system held together by its own gravity. It is a measure of the total energy content that keeps the object from dispersing. The gravitational binding energy takes into account the gravitational forces holding the object together.
On the other hand, mass defect is a concept from nuclear physics that refers to the difference in mass between a nucleus and the sum of its individual nucleons (protons and neutrons). It represents the amount of mass that is converted into binding energy when nucleons come together to form a nucleus.
In both cases, the binding energy or mass defect arises from the fundamental forces at work. In the case of gravitational binding energy, it is the gravitational force, and in the case of mass defect, it is the strong nuclear force.
The key difference is that gravitational binding energy is associated with the gravitational interaction between objects on a macroscopic scale.
On the other hand side, mass defect is specific to the binding energy of nucleons within an atomic nucleus on a microscopic scale.
While gravitational binding energy and mass defect are related concepts that both involve the binding energy of particles, they refer to different phenomena on different scales—the gravitational binding energy at a macroscopic level and the mass defect at a nuclear level.