Lady Macbeth and Lady Macduff are similar in that they expect their husbands be protect and rule their families. When Macbeth is considering whether or not to kill Duncan, Lady Macbeth tells him that he would be more the man if he were to go after his ambitions. She expects that he would do whatever is necessary to advance their family's position. Similarly, in Act 4 when Lady Macduff learns that Macduff has fled the country, she is angry with him for not staying behind to protect his family. She thinks that he has made himself look like a traitor, and she feels that he is now worthless in his role as husband and father. Despite these similarities, the two women are quite different in that Lady Macduff appears to have a good nature whereas Lady Macbeth exhibits a more evil, ambitious nature when plotting to kill Duncan.
Lady Macbeth and Lady Macduff are similar in the sense that the death of each is caused by the actions of their respective husbands. Lady Macbeth commits suicide because Macbeth has gone too far in his pursuit of power and she can no longer deal with the guilt she feels over her role in his transformation from a hero to a murdering despot. Lady Macduff has been left behind by her husband, who has fled to England to find help in his rebellion against Macbeth. Macbeth takes advantage of his absence and sends men to murder Macduff’s servants, wife, and children.
Their differences, however, are more striking. Lady Macduff did nothing to deserve her fate, while Lady Macbeth goaded and manipulated her husband into killing King Duncan. From that point forward, Macbeth was consumed with the need to protect his power and position.
It is ironic to note that Lady Macbeth’s suicidal guilt was in large part caused by Macbeth’s murder of Lady Macduff. In Act V, Scene I, as she sleepwalks and tries to clean imaginary blood from her hands, she says:
The thane of Fife had a wife: where is she now?
This is a reference to Lady Macduff. It is not clear whether or not Lady Macbeth knows that Lady Macduff was killed by Macbeth, or whether she truly does not know what has happened to her.
In addition to the similarities mentioned in the previous answers, I would also say that Lady Macbeth and Lady Macduff's similarity lies in the fact that they are both left by their husbands. On the one hand, Lady Macbeth is not physically left by Macbeth; however, her husband is consumed by the ambition to protect his position and begins to ignore his wife. Lady Macbeth feels abandoned and is left alone to struggle with the enormous amount of guilt that eventually leads to her descent into madness and death. On the other hand, Lady Macduff is left by her husband when he leaves Scotland in order to seek Malcolm's help to overthrow Macbeth, so she remains unprotected and powerless with no one to help her and her children.
As for their differences, Lady Macbeth is a cruel, calculating woman who manipulates her husband into following through with his plan to kill Duncan, while Lady Macduff is a loving mother who is goodhearted and unlike anything that Lady Macbeth is characterized by. The two of them are total opposites. Nevertheless, the deaths of both are seen as moments of profound tragedy.