What were the material differences such that the USSR was able to use central planning to develop their economy into a superpower, while the Chinese economy struggled to alleviate poverty without seeking foreign investment?
(I get that the question presupposes legitimacy of the Deng reforms and I am too much of an ignoramus to argue one or the other, so if you think the question is a fundamentally incorrect one I'm interested to know why too)
USSR was far, far wealthier than PRC as they were coming from a strong Russian empire while the PRC was coming from a colonized, occupied, and heavily imperialized China
When the PRC was just founded, China's GDP per capita was lower than most African countries