Aims. We aim to characterize the spatially resolved stellar population and emission-line properties of galaxies in the M51 group using the same methodology previously applied to the M101 group, ultimately seeking to understand how environmental processes shape the physical properties of galaxies by comparing the results obtained for different groups. Methods. Properties were derived by applying the ALSTAR spectral fitting code to multiband datacubes from the Javalambre Photometric Local Universe Survey (J-PLUS) data. Results. We present spatially resolved maps of the main stellar population and emission-line properties for the M51 group galaxies. The interacting pair M51a/b displays clearly distinct properties: M51a features prominent star-forming spiral arms, while its companion is essentially an early-type retired galaxy. M63 exhibits significant asymmetries in its stellar age, dust attenuation, and Hα equivalent width distributions, showing signs of outside-in quenching, likely due to a past interaction. Relations between physical properties and the stellar mass surface density (Σ★) were investigated. The age─Σ★ and nebular metalicity─Σ★ relations are flatter than those in the M101 group. Also, unlike in the less dynamically evolved M101 group, all galaxies align with the resolved star-forming main sequence, with the exception of M51b, which has all the traits of a retired galaxy. Conclusions. The M51 group presents signatures of more advanced dynamical evolution than the M101 group. This is evidenced by flattened age and nebular metallicity gradients, enhanced dust content, and signs of environmental quenching in some members. In contrast, the less dynamically evolved M101 group largely preserves its primordial inside-out formation signatures. While these findings suggest that group mass and interactions play a role in shaping galaxy evolution even in low-mass environments, the comparison of two systems is evidently limited by small-number statistics. This comparative study underscores the power of J-PLUS data for conducting detailed IFS-like studies of galaxies in the nearby Universe.