Top: comparison of molecular abundances (X = N/H₂) towards G31 (blue bars) and AG318−c9 (orange bars), sorted by molecular groups and by the abundance of AG318−c9 inside each group. The species are grouped on the x-axis according to their detection status. Left: detected in both sources. Middle: detected in G31 alone. The orange triangles represent the corresponding upper limits for AG318−c9. Right: reported in AG318−c9. Bottom: logarithm of the ratio of the abundances of the two sources. HC₃N* represents the group composed of HC₃N, HC₃N (v₆ = 1), HC₃N (v₇ = 1), and HC₃N (v₇ = 2).