How are Beneatha and Walter different from the mother in their outlook on life at the beginning of the play?

Everyone in A Raisin in the Sun dreams. As we meet the Younger family, we meet their dreams. While Beneatha and Walter strive for far-reaching plans, Mama wraps her arms around her family and dreams of owning a home where she can care for them all.
Beneatha plans to become a doctor, always an impressive dream; in the mid-1900s, for an African American woman, this was a rare reality. Mama encourages and supports her, even as Beneatha spouts ideas Mama does not agree with. Beneatha wants to try new things too: guitar, horseback riding, photography. She is not content.
Walter wants to be an entrepreneur, with an idea of owning a liquor store. Mama clearly cares about her son but cannot get behind this idea of selling liquor. For Walter, this dream is about more than the literal store; it is about owning something and opening up more of the world for his son. He, too, is not content.
Mama's dream is a home for her family. She does not look for a new job or new ideas or a risk. Instead, she confides in Ruth she might spend her husband's insurance money on "a little old two-story somewhere, with a yard where Travis could play in the summertime." While her children are reaching for what more is out there in the world, Mama narrows her focus to a physical place to protect her family. This is not to say her dream is not reaching for more. In fact, home ownership is part of the American Dream. She sees the way to help her family differently than her children do, though. When this dream later becomes risky, we see Mama's determination and focus.