In both "The Necklace" and "How Much Land Does a Man Need?" the viewpoint character is dissatisfied and wishes for better things in life. Mathilde Loisel would like to have a mansion, a carriage, liveried servants, distinguished guests, and a generally higher life style. She would also like to be admired.
Mathilde suffered ceaselessly, feeling herself born to enjoy all delicacies and all luxuries. She was distressed at the poverty of her dwelling, at the bareness of the walls, at the shabby chairs, the ugliness of the curtains.
Pahom wants more land. This would make him rich, because he couldn't use all the land himself and would rent it out to others. He would become a distinguished person and would be envied and admired.
The one drawback of peasant life, he declares, is that the peasant does not have enough land: “If I had plenty of land, I shouldn’t fear the Devil himself!”
That is one similarity between the two stories. Another similarity is that both protagonists get unexpected opportunities to realize their wishes. Both seem to be achieving what they had hoped for, although Mathilde's success is only temporary. Pahom has a chance to acquire a huge tract of rich land such as he has always wanted. Possibly Mathilde's one-night success might lead to better things for herself and her husband. She has been seen and admired by important members of society. There may be more invitations. Her husband might receive a promotion.
The third similarity is that both stories end in disaster. Pahom kills himself by overexertion. Mathilde loses her charm and beauty in working to pay for a fake diamond necklace. The morals of each story seem to be similar. It might be stated as: Wanting too much out of life always leads to disappointment and disillusionment. If Mathilde had not lost the necklace, it seems unlikely that she would not have wanted more opportunities to enjoy the amenities of social privilege. In this respect, she and Pahom are very similar.
Both Maupassant's and Tolstoy's stories are obviously didactic and moralistic. We identify with both of the underprivileged protagonists and feel pity for them when their hopes and dreams are shattered.