However, if you have been browsing through the App Store recently, you may have also come across a new set of apps that are indicated by a '+' sign.
These are a new type of applications called "Universal apps" that have been designed for both the iPhone, iPad and iPod Touch. Unlike the majority of apps in the App Store that are basically blown up in size while accessed via the iPad, these universal apps are designed for the iPhone, iPod Touch as well as the iPad.
The universal apps are indicated by a '+' sign to the left of the application's price in the search results:
If you are in the application description page then the left-side column will read "This app is designed for both iPhone and iPad" underneath the app's icon and price as seen below:
Elia Freedman from Infinitiy Softworks, developer of apps such as powerOne provides some clarity on what does it mean to us as users:
First, a universal app is a single app that functions on iPhone, iPod touch and iPad. It is one app, not two separate ones, that knows how to react to the device appropriately.
Second, the App Store cares about your account, not your computer. If you buy an app on your iPhone and want to install it on an iPad, you an either sync it to your computer or "re-purchase" in the iPad App Store. Because both devices are attached to the same account, Apple recognizes that you already purchased and doesn't charge you again.
Finally I'd mention that you don't need an iPad specific app as the iPhone apps will work on the iPad (although it definitely won't look as nice).
As folks at ReadWriteWeb note, this is effectively a "buy one, get one free" offer except that in this case both applications bundled into one download. Universal apps currently available on the App Store include Pandora, Instapaper Pro, Evernote, WordPress, LogMeIn Ignition, IMDb and Now Playing.
The universal apps are a great way for users who own multiple Apple devices like iPhone, iPod touch or iPad to use applications on these different devices for a just one price.
Hope this article has provided the required clarity on the universal apps. Do let us know how these apps compare on different devices in the comments section.