The Samsung Galaxy S6, the latest flagship from the South Korean tech giant, is undoubtedly outselling the Galaxy S5. But it is struggling to rival Apple's iPhone 6, reports the Wall Street Journal, citing a market analysis from Counterpoint Technology Market Research of Hong Kong.

In the United States, the Galaxy S6 and the Galaxy S6 Edge that comes with a dual-edge curved screen went on sale April 10. Three weeks after their release, the South Korean company shipped 10 million units to its distributor and retail partners. It could manage to sell around 6 million units to end users, predicts Counterpoint.

Sales of the Galaxy S6 and the S6 Edge have easily surpassed those of the Galaxy S5 in the same period. Even though Counterpoint does not specify how many iPhone 6 and iPhone 6 Plus units were sold in April, it states that Samsung could sell fewer units of the Galaxy S6 and the S6 Edge in the same month.

The Wall Street Journal adds that Samsung claims the new flagships are very much in demand and the company is concentrating on production of the dual-edge screen variant to support further growth. However, the company did not reveal exact figures. WSJ states that Samsung rarely reveals sales information for its individual smartphones.

Even though it has been eight months since the iPhone 6 and the iPhone 6 Plus were released, both Apple flagships remain quite popular. Analysts cite the strong brand presence and Apple’s first attempt at launching iPhones with larger display screens.

In the spring, Samsung informed its investors that the demand of the Galaxy S6 Edge would be lower than that of the Galaxy S6. However, the popularity of the Galaxy S6 has been such that it has surpassed demand. Hence, producing more number of Galaxy S6 Edge units have proven to be a challenge. In April J.K. Shin, CEO of Samsung Mobile, was compelled to announce that it would take more months to produce enough Galaxy S6 Edge units to meet the high demand.