Until now, providing an experimental unambiguous proof of the CR origin has been elusive. The SNR study showed an increasingly complex scenario with a continuous rielaboration of theoretical models. During its five years of life, the AGILE (Astrorivelatore Gamma ad Immagini LEggero) gamma-ray satellite observed several SNRs, collecting a great amount of data together with Fermi-LAT satellite. Two old SNRs, W28 and W44, seem to be very interesting sources in the context of CR acceleration and propagation: e.g. W44 low-energy spectrum is the first evidence of the neutral pion emission. Moreover if in the one hand the SNR W28 could be well explained by a simple linear DSA model, vin the other one W44 spectrum could be the sum of several contributions from different regions of the remnant. We will do a theoretical and experimental comparison between these important SNRs in order to have a clearer idea of processes that could affect CR acceleration and propagation, and their mutual influence.