particle和atom有咩分別?

In chemistry and physics, an atom (原子) is the smallest particle (粒子) of a chemical element that retains its chemical properties. Until the advent of quantum mechanics dividing a material object was invariably equated with cutting it.)
Whereas the word atom originally denoted a particle that cannot be cut into smaller particles, the atoms of modern parlance are composed of subatomic particles:
electrons, which have a negative charge, a size which is so small as to be currently unmeasurable, and which are the least heavy (i.e., massive) of the three;
protons, which have a positive charge, and are about 1836 times more massive than electrons; and

neutrons, which have no charge, and are about 1838 times more massive than electrons.

Besides its common definition, particle may refer to:
In chemistry:
Molecule; Atom; neutron; Photon; Colloidal particle in colloid chemistry (a one-phase system of two or more components);
In physics:
Subatomic particle, which may be either:
Elementary particle, a particle of which larger particles are composed, also called a fundamental particle;
Composite particle, a bound state between several elementary particles;

Point particle, an idealized particle that does not have any volume;

In summary, they mean the same thing in some text books/documentation.