  The global structure of galaxy clusters and its evolution are tested within a
large set of TREESPH simulations, so to allow a fair statistical comparison
with available X-ray data. Structure tests are based on the "power ratios",
introduced by Buote & Tsai. Cosmological models considered are CDM, LCDM
(Omega_L=0.7) and CHDM (1 mass.neu., Omega_h = 0.2). All models are normalized
to provide a fair number density of clusters. For each model we run a P3M
simulation in a large box, where we select the most massive 40 clusters. Going
back to the initial redshift we run a hydro-TREESPH simulation for each of
them. In this way we perform a statistical comparison of the global morphology
of clusters, for each cosmological model, with ROSAT data, using Student
t-test, F-test and K-S test. The last test and its generalization to 2--D
distributions are also used to compare the joint distributions of 2 or 3 power
ratios. We find that, using DM distribution, instead of gas, as done by some
authors, leads to biased results, as baryons are distributed in a less
structured way than DM. We also find that the cosmological models considered
have different behaviours in these tests: LCDM has the worst performance. CDM
and our CHDM have similar scores. The general trend of power ratio
distributions is already fit by these models, but a further improvement is
expected either from a different DM mix or a non-flat CDM model.
