I think that both characters in Hansberry's drama experience a level of fulfillment and deferral in regards to their dreams. Beneatha is able to exercise her fundamental notion of freedom in being able to achieve her dream of self identity. She is able to use her freedom to define herself in different manners, with different likes or dislikes. Yet, at the same time, she is unable to fully conceptualize who she wants to be. In this, her dreams are activated, but never come to a form of conclusion. This reflects a complex relationship that Beneatha has with her dreams.
Mama Younger represents a more traditionalist form of woman that grasps her dreams' realization has to be based on contingencies such as timing and circumstance. It is in this light where her dreams are a bit closer to being accomplished, but one where there has to be a period of waiting and struggle in order to see them realized. Her dream of Walter moving the family to Clybourne Park and establishing some type of stability with a home is something that she envisions for a while, but must wait. Unlike Beneatha who is not keen on waiting and simply acts, Lena must wait for timing and circumstance and in this, a statement about dreams and their realization could be made.