<p>To investigate the differences in support effects and mechanisms between elastic thin spray layers (TSL) and rigid concrete spray layers (CSL), uniaxial compression tests were conducted on rock specimens with different spray materials and layer thicknesses. The meso-damage evolution of the spray layer–rock composites was monitored using acoustic emission (AE) and computed tomography (CT) techniques. Numerical simulations and field industrial tests were conducted to further analyze the mechanical response and interface behavior of the spray layer. From an energy perspective, the energy distribution and failure sequence of the spray layer, interface, and rock during the collaborative loading process of the two systems are clarified. The results show that both TSL and CSL significantly improve the mechanical properties of rock, but their enhancement mechanisms and effectiveness conditions are different. With increasing spray layer thickness, the peak strength of TSL–rock composites increases linearly, whereas the elastic modulus remains nearly unchanged. In contrast, the peak strength of CSL–rock composites increases exponentially, accompanied by a linear increase in elastic modulus. TSL effectively suppresses macro-crack propagation, promotes stable micro-crack accumulation, and markedly reduces microscopic damage during the compaction and elastic deformation stages. Although local debonding occurs at the spray layer–rock interface, large-deformation compatibility is maintained. The internal crack morphology is predominantly circular, and crack complexity decreases with increasing TSL thickness, forming a more uniform micro-crack system. By contrast, CSL transforms the rock failure mode from unstable fracture to progressive failure. The AE signals shift from high-frequency to low-frequency dominance, and the interface is prone to large-scale debonding and spalling. The rock interior is mainly characterized by a limited number of slender, open primary cracks with a high fractal dimension. Furthermore, the effective support range of TSL increases linearly with spray layer thickness. TSL is more effective than CSL in inhibiting crack propagation in rock. Numerical simulations further demonstrate that TSL and CSL exhibit different energy distributions and cooperative bearing mechanisms. The TSL system utilizes the interface as the primary medium for energy dissipation, with its energy-carrying capacity increasing as the thickness increases. This system operates in a 'flexible coordination' mode, wherein interface debonding occurs prior to rock failure. An increase in thickness can effectively delay interface failure and enhance the energy storage capacity of the rock. In contrast, the CSL system functions in a 'rigid bearing-dominated' mode, where there exists an upper limit to the energy-carrying capacity of the interface. Beyond a critical thickness, the spray layer itself becomes the main energy carrier.</p>