I want to inform customers with email all the details of their orders and I want to be able to show the difference. For example:

    Those items shipped: ...
    Those items cancelled: ...
    Those items ...

`credit memo, hold, invoice, ship, reorder, create returns...` There so many situations. What should be the best way to achieve this?

Still I tried to use events for invoices (`sales_order_invoice_save_after` - `sales_order_invoice_register`):


    public function execute(\Magento\Framework\Event\Observer $observer)
	{
		$order = $observer->getEvent()->getOrder();
		$stateProcessing = $order::STATE_PROCESSING;

		$collection = $order->getItemsCollection();
		foreach ($collection as $item) {
			$this->logger->info('item = '.$item->getName());
			$this->logger->info('	qty_invoiced = '.$item->getData('qty_invoiced'));
			$this->logger->info('	qty_invoicedorig = '.$item->getOrigData('qty_invoiced'));
		}

		return $this;
	}

But quantities are the same, couldn't get the difference.