  This paper compares the statistical features of the sample of discovered
extrasolar planets with those of the secondaries in nearby spectroscopic
binaries, in order to enable us to distinguish between the two populations.
Based on 32 planet candidates discovered until March 2000, we find that their
eccentricity and period distribution are surprisingly similar to those of the
binary population, while their mass distribution is remarkably different. The
mass distributions definitely support the idea of two distinct populations,
suggesting the planet candidates are indeed extrasolar planets. The transition
between the two populations probably occurs at 10--30 Jupiter masses. We point
out a possible negative correlation between the orbital period of the planets
and the metallicity of their parent stars, which holds only for periods less
than about 100 days. These short-period systems are characterized by circular
or almost circular orbits.
