In this work, we theoretically and numerically investigate Rayleigh–Taylor dynamics with constant acceleration. On the side of theory, we employ the group theory approach to directly link the governing equations to the momentum model, and to precisely derive the buoyancy and drag parameters for the bubble and spike in the linear, nonlinear, and mixing regimes. On the side of simulations, we analyze numerical data on Rayleigh–Taylor mixing by applying independent self-similar processes associated with the growth of the bubble amplitude and with the bubble merger. Based on the obtained results, we reveal the constituents governing Rayleigh–Taylor dynamics in the linear, nonlinear, and mixing regimes. We outline the implications of our considerations for experiments in plasmas, including inertial confinement fusion.