Rearrange pictures in Library

If you put pictures in an album you can arrange them as you like. You could select all the pictures in your library and choose File>New Album with Selection to make an album with all your pictures that you can put in any order you like. Putting pictures in an album doesn't use more memory or change the photos at all. And you can delete pictures from an album without removing them from the library.

This graphic shows how photos can be sorted in different views within the library;

In the library you can only sort by date.

You have more options in albums.