One of the many ways in which China is stunningly big is this: it is full of cities that most people outside of China have never heard of, and each of those cities has twice or three times or four times as many people in it as the cities you think are big cities in your non-China countries.
This infographic from Chinfographics.com starts to get at it, listing 60 Chinese cities (including cities in the Republic of China) with populations over 1 million. Nanchang, Jinan, Changzhou—more than 2 million people apiece.
If anything, the graphic undersells the size of the size of the Chinese cities. The population figures are official numbers, and they apply only to the "urban area," meaning "the lighted area that can be observed from an airplane at night." So New York, rather than getting its usual 8.3 million , is granted a chunk of the East Coast megalopolis that covers 21.3 million people.
But just because Montclair, NJ, has more light bulbs than its Chinese suburban equivalent doesn't mean there aren't a few hundred thousand farmers going uncounted in the dark on the Chinese side. Nor does the graphic include the migrant workers who are living in each of these cities by the millions, while still counting as rural dwellers in the census—basically an uncounted Miami, if not a New York, attached to the official population.