Yes, there are two options on how you can track them separately, aimee-braley.

You can indicate it in the Memo section of the invoice to track if it's for an internal or external billing. 

Aside from that, you can also use the Class Tracking feature in QBO. You can use this to get deeper insights into your sales, expenses, or profitability for each part of your business. Once you turn this on, you can assign classes to transactions.

Here's how:

1. Go to the Gear icon and select Account and Settings.
2. Proceed to the Advanced tab.
3. Go to Categories and click the Pencil or Edit icon in the right-hand side.
4. Turn on the Track classes feature.
5. Click Save, then click Done.

One done, create a class for internal and external billing. Here's how: 

1. Go back to the Gear icon and select All Lists.
2. Click Classes.
3. Select New. Create one class for internal, then another one for external.
4. Click Save.

After creating them, assign the class in the drop-down list for Class. 

You can also check out these articles on how you can effectively use this feature in QBO:

• Run Reports By Class
• Create And Manage Classes In QuickBooks Online
• Track Your Transactions By Class

I'll be around if you need more help when creating or tracking your sales transactions.