Two different types of particle state models are discussed. In the first type, particles are considered to be dynamically bound systems of a small set of physical constituents. In the second type, particle states are constructed from tensor products of symmetry constituents, i.e., states that are the basis elements of finite irreducible representations of an internal algebra. These states need not represent physical particles. We present three models of the first type. For the second type, we discuss in detail the main thrust of this paper, a new version of the quark-lepton model based on the algebrasu(4)_flaourXsu(6)_flavour. The quark color-triplet and a lepton color-singlet are united by a single irreducible representation of su(4)_colour. Thesu(6)_colour algebra is an extension of the originalsu(3)_flavor. All observed ground-state hadron multiplets are in full accord with the predictions of this model. The numbers of hadron ground states it predicts are 36 spin-0 mesons, 36 spin-1 mesons, 70 spin-1/2 baryons, and 56 spin-3/2 baryons.