UV curing replaces evaporation with chemistry. A photoinitiator in the formulation absorbs UV energy and fragments into free radicals; those radicals attack the acrylate double bonds in the oligomers and monomers, starting a chain reaction that crosslinks the whole film into a solid network. It happens in a fraction of a second.
The advantages are real: line speeds that thermal drying cannot approach, essentially no solvent, a small energy footprint, and no oven. The constraints are equally real: you need UV equipment, the substrate has to tolerate the lamp's heat, oxygen inhibits the cure at the film surface, and for food packaging, migration of uncured components has to be assessed.
UV is not universally better than thermal drying. It is better where line speed and solvent elimination justify the equipment and the formulation constraints.