Both Stock Adjustment and Receiving increase stock levels in the warehouse.
A Stock Adjustment is an inventory operation used to reconcile the recorded stock balance with the actual stock on hand by adding previously unrecorded items.
Receiving is a transaction that records products received from a specific supplier. A Receiving document can serve as the basis for supplier payments or returns. The value of the received products is included in the Statement of accounts Report. Unlike Stock Adjustments, Receiving allows you to record purchase prices for the received products.
In general, use Receiving to record products purchased from a supplier. Use Stock Adjustments to record items that were found in the warehouse but were not previously accounted for.