There's a huge difference between a products that are very good and products that are simply great. Just like most of the mainstream sound similar, only a few end up at the top of the charts. The difference is in the details.

It's same with mobile apps. Great apps captivate, spread virally, and become part of our lives. Here are some of the elements that constitute a difference between the very good and the great.

1. Great Products are Innovative

Most people confuse innovation with novelty or invention of something new. But in fact, great products are rarely new inventions. For example, Tesla came after Prius and others, Google after Altavista and Yahoo!, Facebook after Myspace and iPhone after Palm and BlackBerry.

The reason many new inventions fail is that there rarely is an existing market for something new, or the state of technology doesn't allow to build a solution that's convenient for customers. Innovation, on the other hand, is when new technology meets an existing market need.

2. Great Products are Simple

As Leonardo Da Vinci already knew "Simplicity is the ultimate sophistication." And there is a good reason most successful mobile products are simple.

Simple products are easy to understand and consequently easy to adopt. That's critically important if you're an unknown brand because users are constantly bombarded with ads for new products and services.

They don't have time to study manuals and learn new behaviours. Thus, the simpler the product, the quicker the adoption.

3. Great Products are Intuitive

Give an iPad to a 5-year-old and the kid will instantly know how to use it. Again, this characteristic of great products goes hand-in-hand with adoption and user experience.

If your users need to read a manual, watch tutorial or contact customer support to figure out how to use it, the chances are it sucks, and they'll hardly get used to it.

4. Great Products are Engaging

The best products engage users to the point of becoming their habits. Credit cards, toothpaste, Facebook, email, they're all parts of our daily habits. We use these products almost subconsciously as part of our daily routine. When products are engaging, they become part of our lives.

5. Great Products Tell a Story

Stories sell because they create empathy and build a connection between your app and the user. And people buy emotionally not rationally.

If you package a product as a bunch of features, you'll have a hard time engaging your users. Instead tell a story about how it can improve a user’s life.

Twitter is not a social networking app; it’s a way to “connect with friends and fascinating people”. Instagram isn’t a camera app with a newsfeed; it’s a way to “share moments with friends”. Quora is not a Q&A site it’s “your best source of knowledge.”

6. Great Products are Useful

Sure, there are stories of useless products that were a financial success. The question is, where are they now? On the other hand, the products that last are products that provide value.

The value isn't necessarily a solution to a problem. Rather it's something that users desire and value enough to spend their money and time on.

7. Great Products are Aesthetic

To add substance to this statement, I'll quote one of the most influential product designers of our time, Dieter Rams. "The aesthetic quality of a product is integral to its usefulness because products we use every day affect our person and our well-being. But only well-executed objects can be beautiful."