Products in AMP are grouped in the Product Catalog in Pages. Pages are represented by a square photo in the Product Catalog. Tapping on a page will bring up a list of products that are grouped under it.
These groupings are controlled by the photos that are matched to the products. If multiple photos share the same photo, they will be grouped together in one page with the photo they share as the group photo.
To group products under a page:
1) Match photos to products using one of our photo matching methods
2) Match the same photo to multiple products to group them together under that photo
A product that has only one photo will stand alone in its own page in the product catalog. Products that have no photos matched to them will group with other products that share the same Collection and Category.