Microsoft's recent introduction of Live Mesh is a perfect example of a core difference between Apple and Microsoft. Apple is, at heart, a product company. Microsoft is, at heart, a platform company. Both produce products and platforms, but the way they approach the problem and communicate with developers is decidedly different.
With Live Mesh Microsoft says, "Come, build on our platform and do amazing things!" What is the oft cited example for using Live Mesh? Multi-device synchronization of data. Now, to be sure, this is a big and very hard problem to solve. In fact, I really wish Apple's Sync Services were much, much better, but do you wake up in the morning thinking, "Man, I really have a Multi-device synchronization problem?" Most people don't. What they do think is, "Man it's great that when I put stuff on the web, I can get it wherever I am. All I need is a web browser." You see, syncing folders or sharing data across devices isn't top of mind in the way a developer thinks about it. Microsoft's challenge is mapping their platform to real problems in a persuasive way.
Contrast this with Apple's normal product focused pattern. First they release a product that solves a real, tangible problem people have. Say, "I hate it that I have to carry around my iPod and my Cell phone everywhere!" or "Man I wish I could buy that cool song I just heard, right now." or "I have so many digital photos, I wish there was an easy way to do something cool with them." or "Man I hate it when I loose files on my computer, I wish I could just go back in time." To solve these problems Apple, like Microsoft, has to build a platform, but this platform is built for a product first, which they use and improve. Then when they talk to developers they can say, "Did you see this cool thing we just did? You can do the same thing or even something better! Here's how we did it..." It's the difference between saying, "Here are the tools, let me show you how to use them." and "I used these tools to do this great thing. Let me show you how and maybe you can do the same thing." Ultimately, it's leadership by example.
Another great example is Apple's use of the Cocoa APIs in their own applications. Apple builds amazing products and then is able to say to developers, "We used the same APIs available to you today!" Contrast this again to Microsoft. Windows Vista was released with some remarkable new C# APIs. Many of them very cool and very interesting, but what is Microsoft Office written in? C and C++. What APIs does Office use? A multitude of Office only APIs and libraries shared among the applications. Does this hurt C# and the new "WinFX" platform "street cred"? I think so.
Ultimately, Apple and Microsoft are trying to solve many of the same problems, but the path you choose while logical to you, may not be so logical to those you most need to persuade and inspire. No one can argue with the results. For me Apple's "solution first, platform second" approach makes for easy understanding of new ideas as well as providing the activation energy needed to try something new.