This paper presents recent selected results from the high-energy heavy-ion collisions from the ALICE and STAR experiments. The study explores the hadron production mechanisms, mapping the Quantum Chromodynamics (QCD) phase diagram, measuring the Quark-Gluon Plasma (QGP) temperature, and searching for the critical point. Additionally, experimental verification of the chiral crossover transition, collectivity in small collisions systems, and recent developments in (anti-) nuclei production are discussed. These findings contribute to our understanding of the early universe and the fundamental properties of strongly interacting matter.