  We have performed large-scale Lennard-Jones molecular dynamics simulations of
homogeneous vapor-to-liquid nucleation, with $10^9$ atoms. This large number
allows us to resolve extremely low nucleation rates, and also provides
excellent statistics for cluster properties over a wide range of cluster sizes.
The nucleation rates, cluster growth rates, and size distributions are
presented in Diemand et al. [J. Chem. Phys. {\bf 139}, 74309 (2013)], while
this paper analyses the properties of the clusters. We explore the cluster
temperatures, density profiles, potential energies and shapes. A thorough
understanding of the properties of the clusters is crucial to the formulation
of nucleation models. Significant latent heat is retained by stable clusters,
by as much as $\Delta kT = 0.1 \epsilon$ for clusters with size $i = 100$. We
find that the clusters deviate remarkably from spherical - with ellipsoidal
axis ratios for critical cluster sizes typically within $b/c = 0.7\pm 0.05$ and
$a/c = 0.5 \pm 0.05$. We examine cluster spin angular momentum, and find that
it plays a negligible role in the cluster dynamics. The interfaces of large,
stable clusters are thiner than planar equilibrium interfaces by $10-30\%$. At
the critical cluster size, the cluster central densities are between $5-30\%$
lower than the bulk liquid expectations. These lower densities imply
larger-than-expected surface areas, which increase the energy cost to form a
surface, which lowers nucleation rates.
