Beyond their titles and genders, Lady Macbeth and Lady Macduff have very little in common. However, one thing they do share is considerable strength and fortitude. But then, as tough, independent-minded women in a male-dominated world, they have to be, whether they like it or not.
Nevertheless, Lady Macbeth and Lady Macduff show their strength in different ways. Lady Macbeth does so by urging her husband on to murder King Duncan when it seems that he's getting cold feet over his part in the murder plot. For her part, Lady Macduff shows her strength by resolving to protect her family after her husband takes off down South to join with other anti-Macbeth rebels.
A further opportunity for comparing and contrasting the two women comes in their relation to what is right and wrong. Although both women are determined to do what they believe to be right, they have a radically different understanding of what's right and wrong. For Lady Macbeth—initially, at any rate—it is right to have Duncan killed. For Lady Macduff, on the other hand, it's right to do whatever she can to protect her children.
In the end, however, the strength of these women avails them nothing. Both find themselves at the mercy of events beyond their control, which leads to their untimely deaths.