The terms "nuclear force" and "strong force" are often used interchangeably, but strictly speaking, there is a subtle distinction between them.
The strong force, also known as the strong nuclear force or the strong interaction, is one of the fundamental forces in nature. It is responsible for holding atomic nuclei together. The strong force acts between quarks, which are elementary particles that make up protons and neutrons, and it is mediated by particles called gluons. The strong force is exceptionally powerful at short distances, overcoming the electric repulsion between protons in the nucleus and binding them together.
On the other hand, the term "nuclear force" refers specifically to the residual effect of the strong force that acts between nucleons (protons and neutrons) within an atomic nucleus. While the strong force is responsible for the binding of quarks inside individual nucleons, the nuclear force is the residual effect of the strong force acting between nucleons, holding the nucleus together as a whole. The nuclear force is also mediated by gluons, but its range is limited to a few femtometers (10^−15 meters), making it a short-range force.
In summary, the strong force is the fundamental force that binds quarks inside protons and neutrons, while the nuclear force refers to the residual effect of the strong force acting between nucleons in an atomic nucleus. The nuclear force is an expression of the strong force at the nuclear scale.