  A high number of embedded clusters is found in the Galaxy. Depending on the
formation scenario, most of them can evolve to unbounded groups that are
dissolved within a few tens of Myr. A systematic study of young stellar
clusters showing distinct characteristics provide interesting information on
the evolutionary phases during the pre-main sequence. In order to identify and
to understand these phases we performed a comparative study of 21 young stellar
clusters. Near-infrared data from 2MASS were used to determine the structural
and fundamental parameters based on surface stellar density maps, radial
density profile, and colour-magnitude diagrams. We obtained age and mass
distributions by comparing pre-main sequence models with the position of
cluster members in the colour-magnitude diagram. The mean age of our sample is
~ 5 Myr, where 57% of the objects is found in the 4 - 10 Myr range of age,
while 43% is < 4 Myr old. Their low E(B-V) indicate that the members are not
suffering high extinction Av < 1 mag), which means they are more likely young
stellar groups than embedded clusters. Relations between structural and
fundamental parameters were used to verify differences and similarities that
could be found among the clusters. The parameters of most of the objects have
the same trends or correlations. Comparisons with other young clusters show
similar relations among mass, radius and density. Our sample tends to have
larger radius and lower volumetric density, when compared to embedded clusters.
These differences are compatible with the mean age of our sample, which we
consider intermediary between the embedded and the exposed phases of the
stellar clusters evolution.
