  Recent experimental results in proton-proton and in proton-nucleus collisions
at Large Hadron Collider energies show a strong similarity to those observed in
nucleus-nucleus collisions, where the formation of a quark-gluon plasma is
expected. We discuss the comparison between small colliding systems and
nucleus-nucleus collisions, for: a)~the strangeness suppression factor
$\gamma_s$ and yields of multi-strange hadrons; b)~the average transverse
momentum, $p_t$, with particular attention to the low $p_t$ region where soft,
non-perturbative effects are important; c)~the elliptic flow scaled by the
participant eccentricity. The universal behavior in hadronic and nuclear high
energy collisions emerges for all these observables in terms of a specific
dynamical variable which corresponds to the entropy density of initial system
in the collision and which takes into account the transverse size of the
initial configuration and its fluctuations.
