Relative age difference Δt/t = (t_BaSTI − t_LPCODE)/t_BaSTI as a function of the luminosity for the 0.55   M_⊙ carbon-core sequence. The case with the standard input physics of the two codes (detailed in Sect. 2) is displayed as a solid line. No latent heat release upon crystallization is included, and an Eddington T(τ) relation is employed for the outer boundary conditions. Selected ages from the BaSTI model are also marked at representative luminosities. Dash-dotted and dashed lines display additional comparisons by changing the EOS in the model calculations (see text for details).