gistfile1.cs

public class ProductDetailTranslator
    {
        public ProductDetail Translate(string xmlFrom)
        {
            var productTo = new ProductDetail();
            var xmlReader = XmlReader.Create(new StringReader(xmlFrom));
            var productDetail = XElement.Load(xmlReader);

            var parentGroups = productDetail.Elements("Grouping").First().Elements("section")
                .Select(parentGroup => new Group() { Name = parentGroup.Elements("displayname").First().Value, Items = GetChildren(parentGroup).ToList() });

            productTo.Groups.AddRange(parentGroups);
                        
            return productTo;
        }

        private IEnumerable<GroupItem> GetChildren(XElement parentGroup)
        {            
            var groups = parentGroup.Elements("groups").First().Elements("group")
                .Select(group => new GroupItem() { IsParent = true, Name = group.Elements("displayname").First().Value, Children = GetAttributes(group).ToList() });

            return groups;
        }

        private IEnumerable<GroupItem> GetAttributes(XElement group)
        {
            var attributes = group.Elements("attributes").First().Elements("attribute")
                .Select(attr => new GroupItem() { IsParent = false, Name = attr.Elements("displayname").First().Value });

            return attributes;
        }
    }