IPhoto Places

Smart albums do not store the photos. They are just referencing the photos in the library. If you delete an album or a smart album, the photos will remain in the library. This is different for the events. If you delete an event, the photos in the event will also be deleted. But you can delete albums or smart albums, and the photos will remain in your library and in the other albums, that are using these photos. The photos in the albums are not duplicates; a photo vcan be in many albums without using additional storage.

If the album has an icon of a folder with a gears badge and is in the Albums section of the sidebar in iPhoto, it is a user defined smart album. To check this album, ctrl-click it and use the command "Edit smart album". You can see the rules used for this album. If you like it, keep it. If not, delete the new smart album.

If the icon of the new album is simply the gears icon and not a folder with a gears badge, it looks like you were using Photos for Mac and not iPhoto. Are you using iPhoto or Photos?

In iPhoto smart albums look like this:

You're welcome 😊