The key difference between muons and mesons is that muons are a type of elementary particles which have no substructure whereas mesons are a type of hadronic subatomic particles which have a pair of quark and anti-quark particle.
Muons and mesons are two types of particles in matter. Muons are a type of elementary particles such as electrons, and we cannot divide them further into smaller structures (such as quarks). But mesons are somewhat larger than muons and contain quark and antiquark particles; thus, they fall under a different category called hadronic subatomic particles. The term hadronic means indicates that it contains two or more quark particles, and subatomic particles are smaller structures than toms, which build up the structure of an atom.
