Compare the two documents against your case record, then contact the issuing government agency using independently verified official contact details. Check the case number, beneficiary, payment stage and amount. An official agency may send a direct notice as well as portal instructions; a discrepancy requires confirmation, not an assumption that either format automatically controls.
Building a record of what was actually asked
Keep the emailed instruction, the headers, and any recorded call, and save the portal document as retrieved with its date. If the difference is a digit in an account number, the answer is a correction from the issuing channel, not a guess. Do not forward the disputed figures to your bank as though settled.
Where the mismatch cannot be resolved, hold the transfer and put the question in writing. Save each document in the form it arrived, including the email headers and the file exactly as downloaded, and note the date and channel on which each reached you. A screenshot of a portal page is weaker than the document retrieved from the portal, and a forwarded message is weaker than the original.
Where the two differ, list the differences as a short table — payee, account, amount, currency, reference, stage — because a table shows at a glance whether one field changed or the whole instruction did. Send that table to the issuing agency as your question, rather than asking in general terms whether the notice is genuine, since a specific question tends to be answered specifically.