  Compression in giant molecular cloud (GMC) collisions is a promising
mechanism to trigger formation of massive star clusters and OB associations. We
simulate colliding and non-colliding magnetised GMCs and examine the properties
of prestellar cores, selected from projected mass surface density maps,
including after synthetic {\it ALMA} observations. We then examine core
properties, including mass, size, density, velocity, velocity dispersion,
temperature and magnetic field strength. After four Myr, $\sim1,000$ cores have
formed in the GMC collision and the high-mass end of the core mass function
(CMF) can be fit by a power law $dN/d{\rm{log}}M\propto{M}^{-\alpha}$ with
$\alpha\simeq0.7$, i.e., relatively top-heavy compared to a Salpeter mass
function. Depending on how cores are identified, a break in the power law can
appear around a few $\times10\:M_\odot$. The non-colliding GMCs form fewer
cores with a CMF with $\alpha\simeq0.8$ to 1.2, i.e., closer to the Salpeter
index. We compare the properties of these CMFs to those of several observed
samples of cores. Considering other properties, cores formed from colliding
clouds are typically warmer, have more disturbed internal kinematics and are
more likely to be gravitational unbound, than cores formed from non-colliding
GMCs. The dynamical state of the protocluster of cores formed in the GMC-GMC
collision is intrinsically subvirial, but can appear to be supervirial if the
total mass measurement is affected by observations that miss mass on large
scales or at low densities.
