The EVO 152 is a single lens helmet with the Visor on the outside of the helmet. The difference is the wearer's ability or need to wear prescription glasses. While many pilots and crew were glasses and are able to use the EVO 052, the EVO 152 is more comfortable to wear for those individuals.
Large frame prescription glasses tend to block the proper drop down of the internal lens and makes the cost of having the 052 or the 252 a waste of money. With the 152, you can still wear glasses and not have the problem with the visor hitting your glasses.
Mose other helmets such as the Gentex SPH-5. HGU 56 and others stack all the lenses on the outside of the helmet. The EVO has a much lower profile by installing the second lens on the inside. It reduces the weight of the helmet and allows for the helmet to fit closer the wear's face and head. The loss of one lens is not that big a deal since most people only use one lens when they fly.