Based on numerical modeling, we compare laser ablation and spark discharge as promising methods of nanoparticle formation. First, we consider spark discharge between parallel plate metal electrodes. Second, we investigate nanosecond laser ablation of a metal target. For both phenomena copper is chosen to be nanoparticle material and argon at atmospheric pressure is used as an ambient gas. Despite different energy inputs, both differences and similarities are revealed in the corresponding plasma properties. The time-evolution of the critical particle sizes are, however, found to be similar in both cases.