Those who follow Jim Cramer regularly know that he loves industries that are dominated by two gigantic players, known as duopolies. In the home improvement space, Lowe's and Home Depot have cornered the market, and lately Cramer has witnessed a strange change in the industry.

For a long time, Home Depot was considered to be the undisputed best-of-breed company, and Lowe's has always been a close second. That domination changed this past earnings season when Lowe's wowed Wall Street.

"Suddenly Lowe's is the new golden boy, and Home Depot is more like the whipping boy," the "Mad Money" host said.

How the heck did Lowe's manage to overtake its one real competitor?

The metric in retail to watch is same-store sales. Last year, both home improvement stores posted same-store sales numbers that were strong, however Home Depot appeared to be pulling away from Lowe's, particularly in the U.S.

After years of generating numbers that were similar, Home Depot finally pulled ahead of Lowe's with 9.5 percent revenue growth.

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Even in February when both companies reported fourth-quarter results, it seemed clear to Cramer that Home Depot was the top dog. Yet, in a matter of months, Home Depot has managed to lose some of its luster.

Simply, when both companies reported last month, Lowe's was able to deliver much stronger numbers.

For the first time in several quarters, Lowe's had better total same-store sales, up 7.3 percent versus 6.5 percent for Home Depot. Additionally, Lowe's posted 40 percent earnings per share growth, more than double the 19 percent growth rate from Home Depot.

The best part to Cramer is that Lowe's stock is still cheaper, selling for just 17 times next year's earnings while Home Depot trades at 18.4 2017 earnings estimates.

Following these earnings reports, Cramer's enthusiasm toward Lowe's grew and pulled away from Home Depot. It seemed to him that practically overnight, Wall Street has switched sides to focus on Lowe's, too.

"While I like both stocks, I have to respect the changing of the guard and tell you that I prefer Lowe's right here. That said, if Home Depot gets clocked back to the low $120s, we may need to recalibrate," Cramer said.

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