While Google Shopping Product Category and Product Type have similar functionality and goals they are different in how they have worked in the past and today.
What’s The Difference Between Category and Product Type?
Google Product Category (google_product_category )is a product feed attribute that categorizes your product into the Google taxonomy.
Product type (product_type) is a product feed attribute that categorizes your product however choose to do so.
Up until March 2019 the google_product_category was a required attribute in product feeds and you needed to categorize your products in one the published categories which you can see a full list of here. Product type has never been required, meaning your products would be approved and eligible for advertising but has always been an attribute that should be completed and optimized.
Why Isn’t Google Product Category Required Anymore?
One reason is that Google is pretty good at categorizing products themselves. If you don’t submit a a product category or if enter a category that doesn’t exist or is incorrect Google will automatically apply one themselves. In some testing I have done the categories Google has selected has been correct. Keep in mind that the products I tested this on had optimized titles, descriptions.
If you looks in merchant center at a specific product you can see if the product was categorized for you.
I looked through all of the products that were automatically categorized and in every case what was selected is exactly what I would have selected.
I have not seen any resources on how they do this but I would guess they are using a mixture of analyzing the other attributes like title and product type and possibly even machine learning to look at the image you submit. Google has a solution called Vision AI that does this as part of their cloud services. I would guess they are using a combination of text and image analysis and the end result in my testing is that the outcome is correct.
The second reason is that Product Category is not the best way to organize products. Simply put the number of product categories in their taxonomy limits how granular a search query can be matched to the best product match. Take the example of a dress. The best product category match would be Apparel & Accessories > Clothing > Dresses but that simple categorization misses a lot of the sub-categories like cocktail dress, maxi dresses, formal dresses, etc that the searcher might be looking for. If you look at the filters in Google Shopping you can see that the filters offered are not related to the product category:
The filters used under style are Cocktail/Party, Casual, Workwear, and Formal/Gown. Instead of relying on Product Category and instead more heavily using Product Type Google can provide better results by offering products that closely match the users intent.
Should I Still Optimize Google Product Category?
Yes, while in limited testing Google assigned the correct category to products that didn’t have a Product Category associated with it, I would still highly recommend categorizing your products. This will ensure that your product is placed into the correct category. If you look at the black dress screenshot above again you will notice the there is a Category filter but Dresses is the only filter. Having the correct category is table stakes to get your products into the main topical bucket that can then be filtered on.
With the change in March 2019 nothing has changed in terms of how you should optimize your Google Product Category, you want to select the most accurate category, in our example your would want to use Apparel & Accessories > Clothing > Dresses not Apparel & Accessories > Clothing or just Apparel & Accessories > Clothing.