The fact that there is both a Photos app and a Gallery app is a tad confusing, and it looks like Google might be getting ready to ditch the Gallery app all together. Ever since the beginning of Android there has always been an app called “Gallery”, which has been the home of all your images loaded on your device. Soon however, the Gallery app will be phased out completely, being replaced by Google+ Photos, or simply “Photos” as the app is called.
Evidence against the Gallery app is mounting, and a high resolution icon for the app was not even created for Android 4.4, even though most other apps did receive a shiny high res icon. Clearly Google would like as many people to migrate towards Google+ as possible, though you aren’t required to create a Google+ account to use the app – it can handle both offline and online photos.