There are a few different reasons why your Airboxr output may not perfectly match Shopify's reporting dashboard.
Refund dates
Airboxr imports the data from your orders and then aggregates them to provide you with the output. We always tag the refund to the original order date. If an order is received in January and refunded in February, we will reduce the sales in January by the value of refunds. On the other hand, Shopify will reduce your sales in February.
As business owners, it is essential for us to know what causes refunds—it is therefore essential to tag the refunds to the right order, instead of the date of refunds. In the above example, if you wanted to find out what drove refunds in January, you can easily do so with Airboxr.
Shopify APIs
Shopify provides access to its data through three developer sources: Rest APIs, GraphQL (short for Graph Query Language), and ShopifyQL. All Airboxr reports are created through GraphQL and all Shopify reports are created through ShopifyQL. This is because ShopifyQL is available for apps that work inside Shopify Admin. Since Airboxr works within spreadsheets, ShopifyQL is not available to us.
Since the data comes from two slightly different sources, some amount of discrepancy is expected. That said, unless your discrepancy is over 10%, it shouldn't affect your decision-making.