The big change is to the user interface. As a report in Droid Life details, Google Play 4.0 features bigger images and a cleaner design.
"The layouts of most pages, including search results, remain mostly the same, however, the eye candy is everywhere," says Droid Life. "Google is using text to separate sections, but then throws big beautiful images and color in your face to grab your attention."
The way the new design boxes items was also compared to Google Now, the company’s “intelligent assistant” for Android that tries to anticipate what information a user might need based on location and other factors before the user requests it.
A more attractive design promises to attract more visitors, but to what extent it will help users discover new apps is for now unknown. Discoverabilty is a major issue for Apple's App Store and Google Play where many apps, among the hundreds of thousands they each contain, don't get a lot of exposure.
While there have been several tweaks to the design of the store, Google Play 4.0 figures to be the first major change since July, 2011. The current version is 3.10.14.