Due diligence is a time-boxed review of earnings quality, debt, contingent liabilities, related-party dealings, tax exposures, and contract risks before money changes hands. Buyers use it to price the deal; sellers use a vendor diligence to close questions before they appear in a data room.
Deliverables are a findings memo, a quantified adjustment schedule where numbers can be supported, and a list of points that should sit in the share-purchase or financing documents.