A decade ago, Apple (Nasdaq: AAPL) was a struggling computer maker on the cusp of reinventing itself, thanks to the imminent launch of iPods, iTunes, and many other hardware and services that would help propel the company to an eventual $585 billion market value.

Back then, Google (Nasdaq: GOOG) was also on the cusp of strong growth, thanks to its impressive search engine. Google's current $400 billion market value is a testament to that company's greatness.

A decade on, Apple and Google have taken aim squarely at each other. Each now offers a mobile phone platform, both companies are using their operating systems and hardware ecosystems to obliterate the traditional PC industry, each firm is gaining strong traction with their entertainment portals (iTunes and Google Play), and each intends to play a key role in the next generation of car stereos.

As these business models converge, it becomes easier to compare these two firms on an apples-to-apples basis. Notably, Apple has become the value play, while in some respects, Google has become the superior growth model.

As an example, Apple is settling into a phase of respectable growth while Google is still in the midst of rapid growth. Google's pursuit of acquisitions explains some of that difference, but Google still appears poised for greater organic growth, for at least the next few years.

Don't focus too closely on the difference in sizes of the revenue bases. Apple derives a high percentage of sales from hardware, which is inherently less valued. Notably, both of these companies are now counting on fast-growing international sales to offset maturity in U.S. markets. Google, for example, saw international sales rise 28% in the second quarter (from a year ago), while U.S. sales rose just 12%.

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Apple vs. Google: Sales Growth

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Although Apple trades near an all-time high, it is far from expensive. Shares sport a double-digit free cash flow yield (which is the inverse of the free cash flow multiple), which is typically found only on companies that no longer have avenues to growth. Google isn't nearly as cheap, but it is still a solid bargain (on a free cash flow basis) when compared to the newest wave of technology growth stocks, such as Facebook (Nasdaq: FB) and Twitter (NYSE: TWTR).

On the other hand, utilizing free cash flow as a metric for Google is a bit unfair. The company is spending so much money on current growth initiatives that it is intentionally sacrificing billions in free cash flow now for an even future payoff. (Amazon.com (Nasdaq: AMZN) is arguably going too far in that direction, and shares are now being penalized for that.) Apple, for its part, is deploying $11 billion toward capital spending in fiscal 2014, up from $8 billion in fiscal 2013.

Apple vs. Google: Valuation

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Of course, nobody is looking to buy Apple right now because it is a value play, nor are investors solely focusing on Google's projected 20% sales growth in 2015 and 2016. Instead, for long-term investors, the value proposition rests on market share -- and in the case of these two firms, market domination.

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Which company will rule the roost? There's no simple answer just yet, simply because we don't yet have a clear read on where these businesses will be a half-decade from now.

Google, for example, is likely to aggressively target the broadband market, which could portend many years of capital spending but a far higher revenue base. If Apple ends up grabbing major market share in the television/video ecosystem, then it will become vastly larger -- and more profitable. And both of these firms believe that an increasing number of household devices can ultimately be managed by their software platforms, which could also lead to another growth spurt.

In the near term, Google creates a bit of a conundrum: The company doesn't march to the cadence of a product cycle, and therefore lacks clear catalysts. Apple, for its part, has launched few hot new products under CEO Tim Cook, but that's about to change.

As analysts at JMP Securities note: "Big picture, we expect Apple to demonstrate much better product innovation over the next several quarters than we have seen over the past several years, and we believe the combination of larger iPhones, Internet of Things applications (including the iWatch and iWallet), and its enterprise thrust can return Apple to a share gain and double-digit growth." They have a $135 price target, which implies nearly 40% upside.

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A key tell that Apple is on the cusp of a major wave of new product launches: In its 10Q, the company noted a 100% jump from the March to June quarters (to $5.6 billion) for "other obligations" for items such as marketing and quality control testing, which has typically preceded new product introductions.

Yet for investors looking for the right time to take profits, this product cycle may prove timely. "Selling the stock on product announcements has been the right approach in recent years," note analysts at UBS, who see shares rising to $115. To be sure, Apple is under the gun to deliver hits. Analysts at Pacific Crest Securities "believe a massively profitable new product is necessary to drive meaningful upside to AAPL. As a result, if new products do not materialize in a huge new profit pool, we are not likely to maintain our 'outperform' rating long into the iPhone 6 cycle."

Risks to Consider: Even with continued strong growth, these stocks won't necessarily rise higher. Recall that Microsoft (Nasdaq: MSFT) delivered solid growth from 2000 through 2010, but its shares barely appreciated in that time. That's because investors looked down the road and saw an era of eventually slowing growth, so the forward multiple steadily compressed for Microsoft, offsetting further sales and profit gains.

Action to Take --> Neither Apple or Google carries a huge amount of risk. They are two great companies that are decimating any would-be rivals, and key metrics such as free cash flow are likely to grind ever higher. But these stocks have already seen their valuations rise by hundreds of billions of dollars over the past five years, and they will need to deliver flawless execution to push their market value higher. If these stocks make another move up in coming quarters, it may be wise to lock in gains and wait for a better entry price down the road.