Shopify App Proxies are a way for app developers to create custom URLs that integrate with their Shopify app's functionality. These URLs can be used to display custom content or functionality within a store's existing theme, without the need for the store owner to install a separate app or make significant changes to their store's code.

In the case of Order Editing, the app creates a unique URL that points to a subdomain on the Order Editing app, as I explained earlier. This URL allows customers to edit their orders using the Order Editing app's interface.

However, if a store is using one of Shopify's themes, they have the option to use Order Editing's widget instead. This widget can be accessed by adding "/tools/order-editing" to the end of the store's URL. For example, if a store's URL is "examplestore.myshopify.com", the Order Editing widget can be accessed at "examplestore.myshopify.com/tools/order-editing".

The Order Editing widget works by using Shopify App Proxies to display the Order Editing app's functionality within the store's existing theme. This allows customers to make changes to their orders without leaving the store's website, which can provide a seamless and convenient experience.

To summarize, Order Editing's unique URL allows customers to edit their orders using the Order Editing app's interface, while the Order Editing widget allows customers to make order edits directly from the store's website using Shopify App Proxies. Both options can provide a convenient way for customers to edit their orders, depending on the store's needs and preferences.