By the time Google introduced its Android mobile operating system in 2008, Apple had been selling iPhones for an entire year, competing mostly with BlackBerry. That head start allowed Apple to develop a large network of iOS developers, as well as a means to get them paid through the iTunes store and advertising. To some extent, Google is still catching up, even though at this point it has a much bigger installed base around the globe than iOS.

When it comes to smartwatches, however, the roles are now reversed. Google's Android Wear will have been on the market for over a year before Apple Watch releases this spring, giving Android a head start with thousands of apps under the Google OS. While some high-profile developers such as ESPN, Instagram and American Airlines have promised apps for the Apple Watch at launch, Apple will be in the unfamiliar position of playing catch-up.

But unlike the early days of smartphones, app ecosystems have been largely established, with most users owning an iPhone or Android device. And since both Android Wear and Apple Watch rely on smartphones running their respective operating systems, the decision between the two may fall largely on what phone a user currently has.

Apple has 380,000 in its iOS program that can potentially make their own apps for the wearable to help play catch-up. “It’s certainly in the interest of OS vendors, because they’re really the ones that define the app ecosystem,” Jeff Orr, senior practice director for ABI Research, said. “To be able to keep wearables inside the same app ecosystem is going to be an advantage for those vendors.”

Much of that momentum is expected to fall behind the Apple Watch and Android Wear because of their large app developer base, Orr added. An advantage Android Wear currently has is that physical devices are currently in the hands of its developers, while most Apple Watch developers have had to rely on simulators and software development kits (SDKs). 

While Android Wear and iOS are expected to dominate the smartwatch app ecosystem, will a new class of device with different apps and use cases allow a third player to break into the mobile duopoly?

The Little Guys

Devices not running on either platform include Kickstarter-funded Pebble, which has seen mild success with its 1 millionth device shipped late last year, and Samsung’s line of Tizen OS-running Gear smartwatches, which last claimed shipments of 800,000 units in 2013. For the smaller players, the competition isn’t necessarily targeted at being a do-all device.

“There’s a lot of discussion by wearable manufacturers about specialization and trying to reach a certain demographic, rather than just being a general computing device,” Orr said. In the fitness and health tracking realm, that’s already seen in practice with the number of wearables you can find in stores, such as the FitBit Surge. Elsewhere, more traditional timepiece manufacturers are also looking to get into the market with certain features -- for instance, Switzerland-based Swatch Group's smartwatch, which doesn’t need to be charged.

Killer App

Apps may be a factor in making the decision of what smartwatch to get. But influencing that decision will also be what smartphone a consumer currently has, since most devices currently on the market tether to smartphones running the same operating system. Android Wear smartwatches only work with Android smartphones, and Apple Watch will only work with some of the latest iPhones running iOS 8. And switching across either could be a costly proposition.

“Suddenly you could have a $1,000 device bill, just so that you can run an app on your wrist,” Roger Entner, lead analyst at Recon Analytics, said. “That’s a tough one to swallow. You’re also in another situation where you have an app library and you have to buy all the apps again.”

Battery Life

Beyond the apps, smartwatches still have a number of problems to solve, particularly when it comes to battery life. Many of the current smartwatches on the market struggle to last more than a day. And the Apple Watch is not exception, with rumors pointing to 19 hours under a mix of active and passive use.

But that isn’t expected to slow the growth of smartwatch shipments, which are forecast to surge 300 percent in 2015, according to ABI Research. Fueling the growth is the Apple Watch, which is projected to take 50 percent market share in the same year. Estimates from several investment firms place Apple Watch's first-year sales anywhere between 10 million and 30 million units.