There are a couple of significant differences. First, Vance wrote his because he was so outside of the "norm" at Yale that a classmate, on hearing parts of his life story, urged him to write it. Vance thought that writing it might help the overlooked woes of poor white communiites devastated by the Clinton-onward outsourcing of our manufacturing to China, and also that the Ivy League and similar elites might consider taking a chance on poor whites.
By contraast, Obama's self-serving book was part of a "strategy" to help him con his way into the presidency, and supposedly was not even written by him, but by Bill Ayers, a hardcore anti-American leftwing communist operative who was part of the cabal working to install Obama as our 3-term president. The rest of their plan was to also include two terms for Hillary, giving them ample time to totally overthrow the Constitution.
Obama's motivations could not have been more opposite than Vance's gratitude that the American Dream was still there enough to have propelled his upward climb. His book expressed his concern for that Dream's endangerment.
Yes, I was being sarcastic by equating Obama’s book to Vance’s.