These folders include folders for selfies and screenshots. Basically the former will contain photos taken by your phone’s front-facing camera. A test conducted by AppleInsider confirmed that there no face-detection algorithm used meaning that the platform basically decides the folder based on which camera mode you are in.
The same is done with the screenshot folder where photos taken by pressing the home and power button (to trigger the screenshot) will be stored in there automatically. Like we said this separation of photos is a much better way to organize photos stored on the user’s phone and we have no idea why it took Apple this long.
That being said if you don’t have iOS 9 installed and you want a better way to search and delete screenshots stored on your phone, there are free apps out there that does the job, such as Screeny which is a free app that scans your phone for screenshots and lets you delete them in batches to help free up space.