1) Both Of Mice and Men and "The American Dream" describe financial independence as a key component of achieving the American dream. While in the poem this is not the most important thing to the narrator, he does note that "My house and car are paid for / I have money in the banks." His children are also "on their own" and "doing well." Conversely, none of the workers in Of Mice and Men have any kind of financial stability or independence. Their greatest dream is to not have to work for anyone else; to be their own bosses.
2) Similarly, both works express the idea that the idea of 'belonging' is important. In the poem, the narrator talks about his children, his family, and the fact that they still are a part of his life. In Steinbeck's novel, when discussing his dream, George outright says: "[w]e’d jus’ live there. We’d belong there. There wouldn’t be no more runnin’ round the country..."
3) Despite the above, both works indicate that the American dream is ultimately subjective. While there are certain key components (see above), Gunderson tells the reader, "Each of us has a benchmark / To make us proud of who we are." In Of Mice and Men, each character has their own dream, and while there are many similarities, there are also differences. For example, Curley's wife also wishes she could have "made somethin' of [herself]," but her dream for doing so is totally distinct from George and Lennie's.
1a) "The American Dream" indicates that the American dream is achievable. For the narrator, his dream has come true because his children have grown into happy, stable adults and are still a joyful part of his life.
1b) Of Mice and Men indicates that the American dream is not achievable to most people. No character in the novel achieves their dream or even comes close to it. Crooks warns them of just this when he says that he has seen hundreds of men with similar dreams, but none of them ever achieve it. Curley's wife remains trapped in her marriage. George and Lennie's dream of the farm dies with Lennie.
2a) "The American Dream" seems to indicate that the chief obstacle to achieving the dream is giving oneself a realistic benchmark. While the narrator has achieved his dream of having a stable and happy family, he also notes that if his aims were higher, he might not feel that he had achieved the dream. He thinks of himself as successful because he has achieved what he wanted, but he expresses some relief that his dream does not hinge on wanting more.
2b) Of Mice and Men indicates that the barriers to achieving the American dream are systemic and ubiquitous; that institutional poverty and social inequity make it impossible for most people to achieve it, no matter how passionate they are nor how hard they work.
3a) To the narrator of "The American Dream," family is a key component to the dream. He is happy because his children are happy and want to be with him. This is related to but not quite the same as the idea of "belonging." For Gunderson's narrator, it is specifically about the children he raised.
3b) Belonging is important in Of Mice and Men, but family is not a necessary component of the dream. Curley's wife actually wishes that she did not have her family so that she could have achieved her dream. George and Lennie have a "found family" in each other, and George's dream dies with Lennie, but the main idea is them being self-sufficient.
4a) "The American Dream" discusses the fact that achieving one's dream does not necessarily mean that life is perfect. The narrator is still missing things in his life: his "poems have not won awards / And [his] novel’s still not done ... [his] weight’s a problem / And his career may be a mess." He is happy, but he knows there is still more out there.
4b) Because none of the characters in Of Mice and Men have achieved the American dream, they do not quite seem to understand that doing so will not solve all of their problems. In fact, Crooks refers to the dream as "heaven." For the men he's talked to, the dream is an ideal, a vision of a perfect life. There is no such thing as unhappiness or burden once the dream has been realized.