You need the same type of visa for Guangzhou and Shanghai. The only area which has a different type of visa is the Shenzhen Special Economic Zone.
My understanding is that at the date of writing, it is still not possible for HK non-residents to get full China visas (as needed for Guangzhou or Shanghai) of any sort in Hong Kong. However, it is apparently now possible for HK non-residents of most passport types to get 5-day Shenzhen SEZ visas on demand at the Lo Wu border. Note though that for UK passports these are expensive (HK$450, I think).