Hard hats are hard hats. Eps and zip mold helmets are helmets. Hard hats are made to absorb multiple impacts with the spongy brock foam liner. They are extremely comfy, breathable and forming to the head. Eps and zip mold helmets absorb impacts by cracking (the way all snow helmets work). Hard hats are not certified, eps and zip mold helmets are certified. They use hard foam liners. Hard hats work well for smaller multiple impacts. Zip mold and eps helmets work well for single, larger "catastophic" impacts.