Answer: The email tag ##ORDERITEMNAME## is for the field "Name your Job" available on product detail page if enabled within product settings ( If the setting "Allow Edit of Product Name on Ordering" is enabled)
The text entered in this field also becomes the value of the Identifier field when the order is placed.
In order to get the name of the actual product the closest tag/variable available in the email notification is ##PRODUCTNAME##.
This will extract the item name or product name in the email notifications.
Please Note: The above tags are not required for New Order email as everything within this email comes from ##CART_SUMMARY## Tag and as a result no standalone tags are required,you might need these tags in the email like Order Item Approved, Order Status Change etc in order to get the indication of item/product name.