Photos is storing each photo only once, but showing the same photos in several albums for different purposes.
You will be seeing the same photos in Imports as in All Photos or Recents.
- Imports is showing all photos you imported to photos, sorted by the date of Import.
- Recents is showing the recently added photos by the date they have been added.
- All Photos is showing all photos sorted by the date they have been taken.
- The Media Type albums are showing subsets of your photos according to the kind of photos, for example Panoramic o Live Photo.
If you delete a photo from Imports, it will vanish everywhere, from All Photos, from Recents, from any album you have added it to.
To save storage delete only photos you do not want to keep, the bad or boring shots.