Inditex,  (IDEXF) the Spanish group behind the Zara global fast-fashion sensation, is blowing the competition out of the water, including Sweden's H&M (HNNMY) .

Four decades after the first Zara store opened in La Coruna, Spain, there are now more than 2,100 outlets in 90 countries. Along with Massimo Dutti and Pull&Bear, they form part of Inditex's 7,085-store, eight-brand clothing empire that's grown into the world's largest, with €20.9 billion ($23.5 billion) in 2015 sales.

Stockholm's H&M, which started in 1947 with a single store in Vastaras, Sweden, today has more than 4,000 stores in 62 markets - mainly the eponymous chain that's also a mall mainstay. It had  180.9 billion Swedish kroner ($21.7 billion) in 2015 sales.

While both are household names around the world, the brands couldn't be more different. H&M is popular with bargain-hunting Millennials that don't mind packed, messy clothing racks and long lines at the cash register, while Zara appeals to a more discerning, slightly older shopper also seeking affordable fashion in a pleasant setting sometimes bordering on the palatial.

And while H&M keeps splashing out on new store openings - with a target of increasing store numbers 10% to 15% a year - Inditex has scaled back its expansion ambitions (to 6% to 8% over the next several years) to focus on quality over quantity.

Instead, the Spanish company is revamping existing sites and opening sites in carefully selected strategic locations, like the new 47,000-plus-square-foot flagship store in New York's SoHo neighborhood, and in the best-trafficked shopping malls at a time when many large U.S. malls are struggling.

Zara "always goes for the best locations, whether in malls or on the high street," said a London-based analyst who asked not to be quoted by name. "They go for the malls with the best locations and natural levels of footfall, and on top of that they have been specking out their stores pretty strongly ... Their stores are incredible."

Add to that a combination of good quality and attractive price points, an ability to pick up on trends and get clothes to stores quickly and frequently thanks to a super-efficient vertical supply chain and manufacturing base in Spain, and it's no wonder Inditex continues to see double-digit compound annual growth in sales and earnings.

Investors also seem pleased. While industry peers including H&M have seen their shares take a beating over the last year, Inditex is up 4.2% over a year ago.

On Friday in Madrid, Inditex was little changed in Madrid at €29.62, giving it a market cap of around €92.5 billion. H&M was up nearly 1% in Stockholm at Skr242 - though with a one-year return of minus 23.7%. It has a market value of Skr400.8 billion.

Both companies put out numbers this past week.

Inditex posted a 12% jump in jump in first-quarter sales to €4.9 billion, driven by same-store sales growth across all geographical markets, and a 6% increase in operating profit to €705 million. It was also a busy quarter for store openings, from the new SoHo store in a spiffed-up 19th-century building to debut stores in Nicaragua and Aruba, right on the Plaza Daniel Leo in the capital of Oranjestad.

Inditex also said that sales in the second quarter so far rose by 15%.

The story was far different at H&M, where group sales rose by 9% in May compared with a year ago.

H&M also released second-quarter figures that fell shy of expectations - sales rose just 2% to Skr46.8 billion, compared to market bets of Skr48.13 billion.

When it puts out six-months figures next week, H&M may say something about expansion plans for the rest of the year, and how it will be able to sustain its frantic pace. In 2015 alone it opened a net 413 new stores, of which 249 were in the fourth quarter, in a year that CEO Karl-John Persson admits was "very expensive."

H&M's latest opening was in Puerto Rico, in the Mall of San Juan, where 1,400 customers lined up for seven hours - though perhaps more to see Latina model Joan Smalls than for the actual shopping experience.

Like its Spanish rival, H&M also continues to expand online in markets where it has bricks-and-mortar locations. But if either brand has the strength to defend itself against e-commerce powerhouse Amazon (AMZN - Get Report) , it's clearly Zara that's "well-suited ... in an increasingly multi-channel world," as Jefferies analysts have noted.

That's not to say that it will be all smooth sailing for Inditex. Barclays analysts currently have an underweight recommendation on the stock, citing a negative mix of lower space growth, adverse exchange rates from increased emerging-markets exposure and "tough" comps, or comparable same-store sales.

But they they do see an upside if Spanish clothing sales prove even more resilient this year and online launches prove a success.