Difference between `categories` and `mainCategories` in Shopware 6?

Question

What are the differences between categories and mainCategories in Shopware 6?

I don't find anything in the references about that difference:

https://docs.shopware.com/en/shopware-6-en/catalogues/categories#category-overview

Nor any hint in the API docs

https://shopware.stoplight.io/docs/admin-api/1653192ca59cb-create-a-new-category-resources

Nor anything in the admin GUI that makes their meaning clear.

Answer 1

categories are all categories explicitly assigned to the product.

mainCategories are optional and only relevant for the SEO settings of a product. Let's say you have multiple categories assigned to a single product. Your SEO-friendly URL should include the breadcrumb of the category for example /clothing/men/tshirts/my-product. Since there are multiple categories assigned, you can decide which category should be used for the breadcrumb by setting the main category. And since you could have a different SEO-URL for each sales channel, there could also be multiple main categories per product, but at most one per sales channel.