Yes there are two types of PKU. They are treated exactly the same. The only difference is that CPKU is the more severe form of PKU, and people with this type of PKU usually have more restrictive diets than those with Hyperphe.
Someone correct me if I am wrong, but I believe most doctors can guess what type of PKU someone has based on their phe levels from the Newborn Screening. The only way to be 100% positive what type of PKU your son has would be by having his specific mutation found through a blood test. This test is very pricey though, and only some hospitals/insurance companies will cover it.