Samsung is the leading smartphone vendor in the world. In the U.S., however, Apple is still top dog — and its lead is growing.

For the quarter ending January 2013, Apple held a 38% share of U.S. smartphone subscribers, according to ComScore’s latest U.S. smartphone market share data. Samsung placed a distant second, with a 21% share. Apple gained 3.5 points of market share, while Samsung’s slice of the pie grew by only 1.9 points.

As went the two giants, so went their respective platforms. Android continued to lead with 52% of the U.S. market, but its share actually declined by 1.3 points over the previous quarter. Blackberry held a 5.9% share and Microsoft only 3.1%, both of them down from the prior quarter. 

 Samsung’s laid-back performance is somewhat surprising given its aggressive marketing efforts. Samsung is spending way more on advertising than Apple. (Of course, Samsung makes a much broader array of products than Apple does — everything from TVs and flat panels to smartphones to chips.)

This year’s Super Bowl was held on Feb. 3, just after ComScore’s numbers were compiled. It’s possible that the reported $15 million Samsung spent on its two-minute Next Big Thing commercial will deliver an uptick in subscriber share in next quarter’s ComScore report. Samsung is also planning to launch its flagship Samsung Galaxy S4 next week with an attendant media blitz. Several Apple blog sites, meanwhile, have pegged August as the release date for the next iPhone

ComScore says 129 million people in the U.S. now own smartphones, a seven percent increase over the last quarter. The news, however, is not good for all vendors. Third-place HTC’s subscriber share fell 1.7 points over the previous quarter. Fourth-place Motorola’s share dropped 1.4 points in the quarter.  

Top image courtesy of Samsung Mobile