The Photo Story page allows you to use star ratings to quickly make layouts with your images. See more about Photo Stories here.
As you can see below, the star rating of the image controls its size and layout. The order of the images in the set is the order that they will appear on the page. So two images rated 3 will be side by side, while images rated 3 and 2 will be on separate lines.
And a description, as well as other information such as the creation date or photographer credit (the star ratings shown here are for informational purposes and do not show up in the page by default).
The aspect ratio of the image is not affected by this layout, so images with different aspect ratios will look like this.
If you want the rows of your Photo Story to be even and regular, it’s best to maintain the original aspect ratio of your images when cropping them.