I am currently designing an Android app that allows users to browser a product database. The database has a defined tree structures with inner nodes representing product categories and leaf nodes representing single products.
I have two separate views for leaf nodes and inner nodes (the inner node displays all direct child nodes, while the leaf node has some more product details).
Now I need to add some sort of hint or clue for to user to distinguish (when viewing an inner node/product category view) whether each entry is another sub-category or a single product.
The subcategories are represented as a GridView with each item showing a representative image and a caption below.
Are there any established hints for this sort of distinction? All I can think of is something like the folder icon vs. some other icon distinction in desktop file managers, but that does not seem sensible here...