Is there a difference between atoms and particles, or are they the same thing?

Atoms and particles are not the same thing. Atoms are the basic units of matter, composed of protons, neutrons, and electrons. Particles, on the other hand, refer to any subatomic particles, including protons, neutrons, electrons, and others like quarks and leptons. So, while atoms are made up of particles, particles themselves can exist independently of atoms.