Tbh they weren't really trying to do the same thing at all. Gorbachev was an anti-communist who was literally trying to end Soviet socialism. In his extreme naivete, he thought the Soviet system could be replaced with a heckin wholesome social democracy - of course, the liberals he unleashed weren't going to allow that. Gorbachev was not at all a Marxist, was not working towards Marxist ends, and had no theoretical understanding - and he was a simp for the West. The CPSU, at that point, was pretty much not Marxist and had very little theoretical understanding. The whole of the party and state apparatus was rotten and completely collapsed.

On the other hand, Deng was a committed Marxist-Leninist with an actual understanding of Marxist theory. Now, you can disagree with the "productive forces determinism" interpretation of Marxism (I do, there are some serious problems with it), but it is an interpretation of Marxism. Deng never had any intention of taking China off of a Marxist path. He basically set up a play where the West would pay to relocate all of their productive facilities to China. This was, of course, not without great risk - capitalists would be gaining more power here. But it was Jiang Zemin, not Deng, who let capitalists into the party and introduced the revisionist "three represents." I think things could have continued to disintegrate here. But I am fairly optimistic about what is going on under Xi, and I have a decent amount of hope that China is going to be able to pull out of this and that Deng's gamble will pay off.

So I think it only seems like Deng succeeded and Gorbachev failed if you think of them as both trying to do market reforms or something like that. But if you think, as I do, that Gorbachev was trying to destroy Marxism and Deng was trying to save it, then I would say that both succeeded.