Samsung (NASDAQOTH:SSNLF) and Apple (NASDAQ:AAPL) are the world's largest smartphone vendors. Samsung's Galaxy brand and Apple's iPhone are ubiquitous. Combined, the firms produced more than one-third of all smartphones sold globally in the second quarter, according to research firm IDC. In terms of total numbers, Samsung's Galaxy brand has sold more units, but it's not as simple as it may otherwise appear.


Apple's iPhone 6s. Image source: Apple.

A straightforward calculation
Fortunately, it's easy to calculate the number of iPhones Apple has sold. The Cupertino tech giant breaks the figure out in all of its quarterly reports. As of the end of last quarter, Apple had sold just under 774 million iPhones since product's debut in 2007. When Apple reports earnings later this month, it's likely that figure will rise above 800 million, as analysts expect the company to have sold around 50 million iPhones last quarter.


Source: Apple quarterly earnings reports.

Which Galaxies count?
For Samsung's Galaxy, the situation is a bit different and not nearly as straightforward. Samsung is a massive business, with many different segments. Management will occasionally give figures, but Samsung doesn't reliably break out its smartphone sales. Third-party research firms provide the best estimate of Samsung's smartphone sales, which have dwarfed iPhone since 2011, when Samsung became the world's largest smartphone vendor.

Based on IDC estimates, Samsung has shipped 1.12 billion smartphones since 2010, when it introduced the original Galaxy S. The problem in a comparision, of course, is that not all of Samsung's smartphones are Galaxies. The majority are, but Samsung has had many other smartphone brands in recent years, such as its ATIV line of Windows Phones. It has sold some cheap Android phones that haven't borne the Galaxy branding, and more recently, it's introduced its Z series of smartphones running the Tizen operating system.


Image source: IDC.

Not every Galaxy smartphone is comparable to the iPhone. Samsung has managed to stay on top of the smartphone market by selling many different models at many different price points. Some of these handsets are adequate for entry-level users, but do not offer specs or features on par with the iPhone. For that, buyers must opt for Samsung's more expensive flagship Galaxy S line. When it introduced the Galaxy S5 early in 2014, Samsung announced that it had sold more than 200 million Galaxy S smartphones. Tens of millions more sales have undoubtedly been added to that figure in the last 20 months, but total Galaxy S smartphone sales are still well below lifetime iPhone sales.

Moving in different directions
Yet shipment and sales figures only tell part of the story. Apple's and Samsung's respective smartphone businesses appear to be headed in different directions. Samsung's smartphone business has been notably weak over the last year. Larger iPhones and ever-increasing competition from other Android vendors have pressured Samsung's mobile business. Earlier this month, Samsung said that its third-quarter earnings would rise from last year, but the gain seems fueled more by its component businesses than by sales of its smartphones.

Apple, meanwhile, has seen steady growth in iPhone sales year after year. Last year's iPhone 6 was particularly well-received, which could challenge Apple's ability to keep growing the business going forward. Still, the iPhone 6s enjoyed the strongest launch weekend in the company's history. Apple should break the 1 billion sales figure before 2017.

Sam Mattera has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Apple. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.