I'm by no means a history buff, so apologies if the premise of my question is incorrect. From what I understand, the policies of both Stalin and Mao were undone by their successors. However, it seems like Mao's reputation within China remained largely intact whereas Stalin and Stalinism became dirty words within the USSR.
I answered a similar question on Mao Zedong's legacy in this post.
My argument in that response and my argument here is that the Chinese regard Mao as the essential leader of the Chinese Communist Party's rise and as the founder of modern China. “For us, Mao Zedong is the founder of our country. We deeply admire him. He lives in our hearts." In this view, arguably, without Mao there would be no CCP or PRC. What someone in the Soviet Union could argue is that without Stalin, the Soviet Union still would've existed.
That's not to say there hasn't been criticisms of Mao in the PRC or by the CCP. "Resolution on Certain Questions in the History of Our Party since the Founding of the People’s Republic of China" is a 1981 report by the CCP assessing the legacy of Mao as well as his shortcomings. You can read it here.
This report was written by a working group by the CCP Central Committee in 1980 under Deng Xiaoping's supervision. The report, Richard Baum argues in China Watcher (2010), was always going to be favorable to Mao. Why?
Because Deng was pragmatic. Even in 1980, after the Cultural Revolution, Deng understood that Maoists remained in the party and could remain an obstacle in his ultimate goal of economic modernization and empowering profit-driven enterprises - "Capitalism with Chinese Characteristics." So while he could denounce the man who caused his fall from power, it would splinter the party and jeopardize the unity necessary to create market reforms.
So Deng signed off on a report that reflected "a consensus view that Mao’s contributions were paramount (70 percent) and his shortcomings secondary (30 percent)" (Baum, 2010, pg. 105). It was a tactic to address the suffering of CCP members and assert the need of something new but also continue the legitimacy of the CCP through a positive memory of Mao as "a great proletarian revolutionary."
"While persisting in the comprehensive error of the “cultural revolution", he checked and rectified some of its specific mistakes, protected some leading Party cadres and non-Party public figures and enabled some leading cadres to return to important leading posts."
So the report said "Yeah, Mao made mistakes" but what he did was ultimately good and he tried to correct his mistakes.