Photos and albums

Albums aren't a bunch of pictures-- an album is just a list of pictures that you've decided have something in common. So a picture can be on the list of three albums and not take up any more room. If you delete a picture from an album, it just removes it from that list. If you delete a picture from the library, it's gone.

Of course, it goes to Recently Deleted, and you get a month to change your mind.

The only albums that will keep the photos when you delete the photo from the library are Shared albums. The shared albums are holding their own copies of the shared photos. But these copies have been optimized for sharing. They are downsized for a small file size and most metadata will be stripped for privacy reasons. you should nit use shared albums to archive your photos - it would be lossy.