Connecting flight to Hong Kong

Hello, I am a Saudi citizen who I am planning to go to Hong Kong with my family, i have checked and we don't need to apply for visa for Hong Kong but our flights will be through Guangzhou for almost 10 hours in both ways, do we need to apply for entry permit for the transit? Also, are we going to change airport to travel to Hong Kong or we will be traveling from the same airport? If we don't need visa for transit can we leave the airport or we need to stay in?