Densifiers vs. Compactors, what's the difference in the name. In my opinion, it is just semantics! Most of the sellers of EPS melting machines refer to their equipment as densifiers or thermal densifiers. It seems many of the manufactures of EPS cold compression systems with screw augers use the term compactors and the sellers of hydraulically driven systems use both densifier or compactor. In the end, all three types of systems, screw, hydraulic and thermal reduce the light weight foam material into dense logs, bricks or patties. All three types of equipment densify and compress so a densifier is a compactor and vise versa.