  We present a comparison of optical and X-ray properties of galaxy clusters in
the northern sky. We determine the recovery rate of X-ray detected clusters in
the optical as a function of richness, redshift and X-ray luminosity, showing
that the missed clusters are typically low contrast systems when observed
optically. We employ four different statistical tests to test for the presence
of substructure using optical two-dimensional data, finding that approximately
35% of the clusters show strong signs of substructure. However, the results are
test-dependent, with variations also due to the magnitude range and radius
utilized.We have also performed a comparison of X-ray luminosity and
temperature with optical galaxy counts (richness). We find that the slope and
scatter of the relations between richness and the X-ray properties are heavily
dependent on the density contrast of the clusters. The selection of
substructure-free systems does not improve the correlation between X-ray
luminosity and richness, but this comparison also shows much larger scatter
than one obtained using the X-ray temperature. In the latter case, the sample
is significantly reduced because temperature measurements are available only
for the most massive (and thus high contrast) systems. However, the comparison
between temperature and richness is very sensitive to the exclusion of clusters
showing signs of substructure. The correlation of X-ray luminosity and richness
is based on the largest sample to date ($\sim$ 750 clusters), while tests
involving temperature use a similar number of objects as previous works
($\lsim$100). The results presented here are in good agreement with existing
literature.
