If Apple's iWatch design brief includes 10 sensors, then the all-but-inevitable smartwatch won't be a simple device. It will be aimed squarely at exercise enthusiasts, quantified-selfers, and anyone concerned about an expanding waist line.

And the iWatch would also be nothing like Android Wear smartwatches from the likes of LG and Motorola. This foreshadows a war between two entirely different philosophies in the wristband space. Apple's proposition: A smartwatch should be dedicated to telling you about what's happening inside your body. Google's stance: A smartwatch should be focused on the world around you.

On Friday, the Wall Street Journal reported that Apple's upcoming smartwatch will include "more than 10 sensors" to track health and fitness activity, according to multiple unnamed sources. The report also backs up an early Reuters article that says Apple's wearable will be manufactured by Quanta Computer in Taiwan. The Journal's anonymous sources say the smartwatch will come in "multiple screen sizes" (the Reuters article only mentions a 2.5-inch display), and that the wearable could be released in October, with shipments hitting between 10 and 15 million units by the end of the year.

Given that more than 51 million iPhone 5 units sold during last year's holiday season, the iWatch--even if it hits 15 million sales--would still be a relatively niche product for Apple. The Wall Street Journal report remains unsubstantiated, of course, but if Apple ultimately goes all-in with a health-focused wearable, it will have a natural companion to its just announced Health app.

That's great product synergy for Apple, but such a wearable would also be pursuing a market that has, apparently, failed to find traction with consumers. According to a January 2014 study by Endeavor Partners PDF, more than half of all people who've purchased a wearable activity tracker have given up on their devices. (This particular wearable category emerged in 2012.) 

The Journal reports that Apple "aims to address an overarching criticism of existing smartwatches that they fail to provide functions significantly different from that of a smartphone." That's a lofty goal, and we might assume that the iWatch's battery of sensors will be able to track our heart rate, skin temperature, and rates of perspiration.

But Samsung already has wristbands that track heart rate, and they don't work very well. And Basis makes the Basis B1, a wearable that tracks all three data points--yet the company remains anonymous to all but a niche collection of quantified-self disciples. 

A 10-sensor iWatch? That's an incredibly ambitious complement of data-collection points. So how will Apple retains its trademark design simplicity in a device that portends to do so much? Not only will the iWatch need to cram a lot of information into a very small display, it will need to make its health and fitness reports easy to understand for mainstream consumers who aren't well-versed in the semantics of biodata.

Still, it's a direction. And it's a direction that's a 180 degree away from where Google is going with simple Android Wear notifications borrowed from the lexicon of Google Now. 

A smartwatch war is brewing. The battle lines are being drawn. Will consumers vote for data that focuses inward, or data that focuses outward? If the answer is "none of the above," then smartwatches will have a problem that no amount of sensors can fix.