Intelligent people with lots of mobile industry experience still debate this topic aggressively, which is understandable given the stakes. All of us in the industry can see users surging toward mobile. The question is how best to serve those users: app or web (or both)? In this post, I’m not going to answer the question. That’s not a cop-out, but rather an acknowledgement that it isn’t simple. Instead,  I’m going to review the factors you should consider before taking the plunge.

I encourage thinking about four things prior to making the app vs. website decision:

1. Addressable market
2. Resources required to design, build, and maintain
3. Capabilities of the finished product
4. User acquisition and monetization

Things like goals and strategy are still vital, though you can apply them equally to either option. What makes these four things unique is that they will produce different answers depending on the choice you end up making. Here’s an overview of each and whether I see the app or the website as having the advantage, noting that smart people will be able to point out exceptions that could reverse the outcome.

Addressable market – Advantage: website

App: because you cannot, for example, take the very same app you built for the iPhone and publish it to the Windows Phone Store without substantial rework, the audience for apps is fragmented. You also need to consider, for example, that apps built for older versions of the Android operating system may not work on Android’s latest release. Rather than imagine the addressable market for apps to be homogenous, it’s best to think of it as a patchwork of devices, with additional investment possibly needed to reach each segment.

Website: because of industry groups such as W3C, the web benefits from standardization. That means, for example, that the web as seen through Internet Explorer behaves much like the web as seen in the Safari. The result is that any device with a modern web browser is likely to be able to access your website.

Resources required to design, build, and maintain – Advantage: website

App: though the skills required to build an app are relatively easy to acquire, building that same app for multiple devices can get expensive and time consuming. Again, any app you build and publish for one device cannot be redeployed to another device without significant changes.

Website: the skills required to build websites are also relatively easy to find, though because websites are less fragmented, it should require fewer resources to build content capable of reaching more users. Web standardization also makes creating websites easier because it gives anyone training for a career in web design and architecture a target at which to aim their ambitions. They know if they can learn to do the things covered by these standards, they’ll be able to make themselves useful.

Capabilities of finished product – Advantage: app

App: The closer you can get to the “metal,” or the guts of a device, the more powerful the product will be. Because many apps are built using what’s called native code, or programming that can speak directly to a device’s hardware, they often are capable of doing more things and working faster than a website. This is really important, because your goals and strategy may give you no choice but to use native code. That means that regardless of any other consideration, you may need to build an app.

Website: Dependent on the power of the browser, websites can do impressive things, including showing video and running animation. However, websites generally have more limited, slower access to a device’s hardware, which inherently caps performance.

User acquisition and monetization – Advantage: toss up

App: I believe apps have clear advantages over websites in their power and options with which to make money. This makes them both attractive to users and developers. Still, I’m calling this a toss-up because discovering apps is so much harder than websites. If I were to use an Android device, for example, to do a Google search to look for an app called Wordament, a popular Xbox Live game, I’ll be able to see that the app exists, though not for my device. Add to that this startling statistic, which shows how many iPhone apps never get downloaded even once, and you see that discovery is a huge challenge. Here’s another example that illustrates the headwinds. Apple used to promote the number of apps available for iPhone and iPad, but you don’t hear that very often these days. That’s because the number has gotten to be too big. The App Store is a retailer with three quarters of a million items available to buy. Discovery depends most of all on merchandising, not search engines. By comparison, a large Wal-Mart has about 100,000 stock keeping units, or SKUs. The Apple App Store and Google Play store are the mobile app equivalent of about eight Wal-Marts placed back-to-back. That doesn’t sound like a good retailing experience for anyone, either customer or vendor.

Website: capable of e-commerce and advertising support, websites are very capable of generating revenue. Yes, there are hundreds times more websites than apps, but search engines make it easy and fast to find the ones you want. Because a website by and large can be made to run on any device, and because smartphones have powerful search engines, it’s possible to optimize and market your website via search and reach everyone, regardless of whether they have an iPhone, BlackBerry, Nokia or Samsung device.

What about you? Have you faced the app vs. website decision? If so, how did you make that decision?