Bruce Greenwald: Now, Amazon I think is completely different. I think, if Apple is a current profit machine, Amazon is trading on vapors. [laughs]

They make no reported profit; the whole story is a growth story. They're buying customers on the theory, presumably, that those customers are going to be profitable in the future. Now, for customers to be profitable you have to dominate segments.

The segment that Amazon has traditionally dominated is, of course, books, music, and video. Well, we know what happened to the music business when it went digital, which is the profit vanished and even Apple doesn't make any money on iTunes.

The same thing is happening to books, with the connivance, by the way, of Amazon. The same thing is happening to video, so their core business is dying. The business that they dominated, where they made all their money, is dying.

What have they decided to do? Go into a lot of businesses where they have no competitive advantage. First they've gone into every variety of retail: TV sets against Wal-Mart and Best Buy, who have better distribution economics...

They can buy the business, but in the long run, unless they can get bigger share than those companies, their pricing is going to be at a disadvantage to those companies, because those companies can distribute the TVs and other devices more cheaply.

Then what did they decide? They said, "Oh, that wasn't a big enough challenge. Let's go after the Oracles and the IBMs and all the companies that do cloud computing, and the SAPs and so on, and the Googles," and they went into that business.

Now, if you think they've got a competitive advantage in that business while they're going after everybody in retail, lots of luck. But then they decided that was not enough, so they decided to go after Apple and the others in the device business.

This looks, to me, like a company that makes no reported profit, which I think is fair, that's trying to buy growth in all sorts of areas where, because it has no competitive advantage, the growth is going to be value-destroying, not value-creating.

Brendan Byrnes owns shares of Apple. The Motley Fool owns shares of Apple, Amazon.com, and Oracle. Motley Fool newsletter services recommend Apple and Amazon.com. 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.