If it wasn't for Samsung's (NASDAQOTH:SSNLF) mammoth advertising budget, its Galaxy handsets may never have emerged as legitimate rivals to Apple's (NASDAQ:AAPL) iPhone.

Although the company hasn't been able to unseat Apple as America's largest smartphone vendor, it has certainly intensified the competition. Shelling out hundreds of millions of dollars, Samsung recruited the brains behind hit comedy films, Dumb and Dumber and There's Something About Mary, to take the fight to Apple, actively mocking its most dedicated customers in a series of wide ranging ads that even earned the praise of Apple's top brass.

But Samsung's best days could be behind it: The ads no longer carry the same biting wit and its handsets no longer dominate the phablet category it helped popularize.

Enter Google (NASDAQ:GOOG) (NASDAQ:GOOGL) -- the search giant's latest ad campaign continues the fight that Samsung started, though in a much more subtle fashion.

Be together, not the same
Initially unveiled in October, Google has been heavily promoting the latest version Android -- Android 5.0 Lollipop -- in a series of television advertisements that emphasize the key advantage of its mobile ecosystem: diversity.

Unlike Samsung, Google is not actively targeting Apple, but the campaign's tag line ("be together, not the same") certainly seems like a jab aimed at Apple's business model. Although the company now offers two flagship iPhones, they differ only marginally (namely the screen size).

In contrast, there are hundreds of different Android handsets, with different screen sizes, price points, and features. Since the beginning, choice has been Android's key selling feature -- more than six years after the release of the first Android-powered phone, that has not changed.

A stalemate?
But despite swamping the iPhone with hundreds of competing devices, the battle between the two ecosystems appears to have reached somewhat of a stalemate. In the US, Android powers just over the half smartphones sold, according to Kantar Worldpanel, roughly the same percentage it held since the first quarter of 2013. Over that same period, Apple's iPhone market share has also held steady at about 40%.

Android's growth has been more robust on a global basis, with emerging market consumers flocking to the cheaper handsets offered by a diverse cast of Android manufacturers. According to IDC, Android's share of the global smartphone market has grown from roughly 75% to about 85% since 2012.

Optionality may be overrated
With Apple likely to report record iPhone 6 sales at the end of the month, Google's fall campaign seems to have accomplished little.

And though there are now several highly regarded Android handsets, the differences between them are arguably modest -- certainly not significant enough to entice iPhone buyers to switch to Google's ecosystem. Sony offers waterproof Android handsets -- Samsung a removable battery. Motorola's flagship Moto X can be designed by the user with custom colors and materials. But iPhone cases and accessories exist to satisfy all these needs -- Android hardware no longer offers any uniquely compelling experiences.

That might change as radical concepts like Samsung's Galaxy Note Edge could bring Google's ecosystem back to the forefront of hardware innovation. But for the time being, "together, not the same" means little when the differences are so minor.

Sam Mattera has no position in any stocks mentioned. The Motley Fool recommends Apple, Google (A shares), and Google (C shares). The Motley Fool owns shares of Apple, Google (A shares), and Google (C shares). 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.