Heterogeneity is and perhaps will always be a thing for China, and part of the question is if the poor parts have any low hanging fruit left to mimic the success of the earlier-developed and now high HDI areas, or have those fruit withered by now.
I left Beijing, Shanghai, and Tianjin out due to the fact that they are governed differently than provinces, as they are under direct administration of the State Council and they are almost 100% urban. This makes them a bad comparison with Thailand as a whole. At a micro level, it might be interesting to compare BKK versus Beijing/Shanghai/Tianjin but Thailand allows free movement and domiciling, so it's not a great comparison.
> the question is if the poor parts have any low hanging fruit left to mimic the success of the earlier-developed and now high HDI areas, or have those fruit withered by now
It's a tough question and depends province to province. The provinces around Manchuria are probably all tapped out, but there might be some opportunity left in Guizhou, Yunnan, Sichuan, and Guangxi, but local and mid-level governance in China (like other middle income countries) sucks.
I have written a lot about this in a previous life, but I'd rather not write a whole Econometrics white paper on HN
https://www.npr.org/sections/parallels/2017/04/16/523632920/...
This can be seen first hand with Beijing+Tianjin versus Hebei.
Those 2 cities were under direct State Council control so it was easier to push economic reforms versus a largely rural province like Hebei, plus they were close enough that it made sense for anyone half ambitious in Hebei to leave for the big city than to stay back.
This is what happened in NY State as well with NYC and IL with Chicago. It's called the primate effect in economics.
The issue is, research into stuff like this and converting it into actionable policy is becoming difficult, as mid and lower level civil servants don't want to deviate from a literal definition of policies or their mandate as administrations have become much more vindictive due to the economic slowdown. Research like this ends up stepping on people's toes.
http://www.kjjb.org/EN/abstract/abstract18771.shtml
http://www.progressingeography.com/EN/10.18306/dlkxjz.2019.0...
https://www.sciencedirect.com/science/article/pii/S187705092...
https://www.sciencedirect.com/science/article/abs/pii/S02648...
If interested, the Stanford Center on China's Economy and Institutions, the China Guiding Cases Project at Stanford Law, the Becker Friedman Institute for Research in Economics at UChicago, and Abdul Latif Jameel Poverty Action Lab at MIT have all been working on the Rural-Urban Divide problem in Developing Countries. Chinese Policymakers tend to work with Stanford and Indian Policymakers tend to work with UChicago and MIT.
Papers and books published by members of these centers would teach you all that you need to know about Developmental Economics (or at least enough for a pre-doc).