Chinese mainland's tariffs are generally heavy, while Hong Kong seems to be a duty-free zone, and many goods have low tariffs or even tax exemption; Therefore, not only mobile phones, but also imported goods are much cheaper in Hong Kong than in China.
hope this helps ...
Licensed goods refer to the iPhone 4； whose sales place is assigned to Chinese mainland; What is sold in Hong Kong is called the Hong Kong Airport. Licensed mobile phones can be guaranteed in many places in Chinese mainland, but not in Hongkong. If there is something wrong with the mobile phone, you can only take it to the seller, and the seller will try to bring it back to Hong Kong for warranty. In addition to this difference, there is basically no other difference between licensed and Hong Kong iphone4. No matter which country or region has the iphone4 version, you can use Chinese mainland's wifi network normally.