How is Elizabeth's attitude toward marriage different in Pride and Prejudice?
In the case of Elizabeth, she truly and honestly believes that marriage should be made for all the right reasons of the HEART and not the pocket.
Even with the entailment looming above her, she prefers to wait for true love rather than to use marriage as a way to be socially acquainted, or to obtain property, a name, or status.
This is the reason why she was so upset with Charlotte after Mr. Collins proposed to her. When Collins first proposed to Elizabeth, she declined on the very basis of her beliefs: She will not marry for any reason other than love.
Yet, when Collins got rejected and moved on to Charlotte, she accepted and confided to Elizabeth that she did it precisely because she felt that marriage is a contract of convenience: After being married, she would possess some property, and the company of Collins was enough for her.
Later on in the novel we realize exactly HOW Charlotte would end up paying for this choice, and how well Elizabeth did for waiting.
No,they do not share the same attitude. Elizabeth would never marry someone just for the sake of being married while Miss Lucas would. Elizabeth would only marry someone she respects and loves. (There are other differences in their character as for example when Miss Lucas pardons Mr. Darcy's bad manners at the dance because he is a rich and important man while Elizabeth dislikes him for it.)
Charlotte Lucas sees marriage as a way of avoiding being a spinster, a place of security and she is prepared to marry a man she doesn't love. At the time when women had no legal rights and no carrier prospects we can hardly blame miss Lucas for her decision. However, Elizabeth refuses to see marriage as anything else from an union of love. She even tries to convince Miss Lucas to change her decision because she doesn't understands how someone could be happy in a loveless marriage. We can see that Elizabeth is being true to herself throughout the novel because she rejects marriage proposals from the man she doesn't love.