Hi
By default the delete operation in an album is “remove from album” (See the image menu). To delete you have to hold down the cmd key (You can see the command change in the menu if it is dropped down while you press/release cmd)
If you remove from album you are not deleting from the library, and the image will stay in other albums, and the all photos view. If you use the CMD button to delete though, then you are deleting the image everywhere.
If you delete an album, you are only removing that album, and the images will stay in the library.
If you want to be extra carful, check the recently deleted view after remove from album or delete album operations.