  The infrared behavior of gluon and ghost propagators in Yang-Mills theories
is of central importance for understanding quark and gluon confinement in QCD.
While simulations of pure SU(3) gauge theory correspond to the physical case in
the limit of infinite quark mass, the SU(2) case (i.e. pure two-color QCD) is
usually employed as a simplification, in the hope that qualitative features be
the same as for the SU(3) case. Here we carry out the first comparative study
of lattice (Landau) propagators for these two gauge groups. Our data were
especially produced with equivalent lattice parameters in order to allow a
careful comparison of the two cases. We find very good agreement between SU(2)
ans SU(3) propagators, showing that in the IR limit the equivalence of the two
cases is quantitative, at least down to about 1 GeV. Our results suggest that
the infrared behavior of these propagators is independent of the gauge group
SU(N_c), as predicted by Schwinger-Dyson equations.
