Those who have got the Android 5.0 (Lollipop) on their devices, may have noticed that, you don’t have a Gallery app, as you had in your Kikat OS. Google has replaced the default gallery app with their official Photos app.
This Photos app allows you to sign in and backup your all device photos with Google Cloud. All your photos are uploaded to Google photos, which are visible at your Google Plus account’s photos directory. Comes loaded with features like Auto Awesome and lot of filters to apply manually. Its available for Android as well as iOS.
But the annoying thing here is that, all the devices photos/pictures are listed here together. No categories depending upon their Folder name, nor stored location like that in previous gallery app.
You can still get the old Gallery app (from Android Kitkat) and install it on your Lollipop device, but after installation, it hides your Google Photos app, unless you sign in to your Google photos account from mobile, via Google plus.
And if you want an alternative gallery app, you can try Quickpic. Its free and has been used by many.