A description of import types

• New Items Import -

This is primarily used to create and manage records. It keeps internal track of the records that it imports, which means that it can later update/create/delete records as they're changed/added/removed in your import file. It's also the only import type that can add/remove variations for variable products.

One limitation of new items imports is that cannot detect/update records that it didn't previously create.

• Existing Items Import -

This is primarily used to update specific data (e.g., stock/price/images/etc) for records that already exist (created manually or by other imports). This import type does not keep internal track of the records it imports, so it cannot delete missing records from the file. It also can't maintain the relationship between parent products and their variations, so it can't be used to add variations to existing products.

If you're updating product variations with this import type, you should make extra sure that these data points are not being updated in the import settings: https://d.pr/nwqacy.

Here is an explanation of what each kind of import can and can't do:

A "New Items" import can:

• Create records.
• Update records that it created itself.
• Delete records (that it created itself previously) when they don't exist in the import file that is in use for the import.
• Add new variations to existing WooCommerce Products (using this option: https://d.pr/i/DoJKHL).

A "New Items" import can't:

• Update records that it did not create (whether they were manually created or created by another import).
• Delete records that it did not create (whether they were manually created or created by another import).
• Reference the Unique Identifier for another import.

An "Existing Items" import can:

• Create new records.
• Update records that it did not create itself (since it does not reference an identifier of its own, but rather, matches records by Title, Content, Custom Field or Post ID).
• Create new products (though I would advise using a "New Items" import to create products instead, due to what that import type can do).

An "Existing Items" import can't:

• Delete records that don't exist in the import file.
• Reference the Unique Identifier for another import (it is meant to match records by one of the four options mentioned above).
• Add new variations to existing WooCommerce Variable Products.