Om Malik, writing for the New Yorker:

Even their products sound remarkably the same. Apple Pay. Android Pay. Apple Photos. Google Photos. Apple Wallet. Google Wallet. Google announced its “Internet of things” efforts, such as Weave and Brillo. Apple came back with HomeKit. Android in the car. Apple in the car. At the Google I/O conference, Google announced app-focussed search and an invisible interface that allows us to get vital information without opening an application. There was an improved Google Now (a.k.a. Now On Tap). Apple announced a new, improved Siri. It also announced Proactive Assistant. Google launched Photos, which can magically sort, categorize, and even search thousands of photos using voice commands. Apple improved its Photos app—you can search them using Siri.

But when it comes to privacy, there’s a major difference.

On Google’s approach to your personal data:

the company must put all of your information inside Google’s gigantic server farms. Google then uses all of this data to make Google Now more personal and perceptive. If you’re texting a friend about dinner, Google will give you restaurant reviews and directions automatically. In the future, it might make a reservation and call a driverless car. The more repetitive you are in your behavior, the more the algorithms learn to automate things for you. Google’s approach has its benefits—the company’s products are free, and you can be fairly confident they won’t break. The cost is in your data, privacy, and lack of control. Someday, Google will want to make money from all these experiences, either through advertising or through transactions that are hyper-tailored to you.

And on Apple’s approach:

Apple’s approach is entirely different. For them, future personalization will be done by using information already on a device. When you search your iPhone, the company’s new Proactive Agent will quickly find content inside the apps on the device and bring it to the forefront. Imagine that you’ve organized a trip on an app such as TripIt, booked flights on United Airlines, and made hotel reservations. The travel plans will be synchronized with your calendar, but you will also get alerts on when to leave for the airport (depending on traffic conditions) and what route to take. When you arrive, your phone will show you your boarding pass. Any flight delays should automatically show up as well. If you like to read certain magazines on the plane, maybe the phone will download them for you in advance. It learns your habits. Plug in your headphones and you’ll get music recommendations based on your location.

Bottom line, Google’s approach is holistic, global. They take all your data, build a big personalized picture of you, your likes/dislikes, preferences, habits, then unapologetically use that data wherever there’s a need. Some of that need is for advertising (to pay the bills), some of that need is to make their services more closely tailored to your needs.

Apple has drawn the line at keeping your data on your device and, if it leaves the device, anonymizing that data. Craig Federighi, speaking about gathering user intelligence during last week’s WWDC keynote, said:

We do it in a way that does not compromise your privacy. We don’t mine your email, your photos, or your contacts in the cloud to learn things about you. We honestly just don’t want to know. All of this is done on-device, and it stays on-device, under your control.

Om compares Apple and Google to the Klitschko twins, two brothers who became great boxing champions. I thought this was a great analogy. The brothers were identical twins, incredibly alike in many ways, but also unique. And so it is with Apple and Google. One went into product design, one went into advertising.