Insert and Update Adapter notifications use exactly once notification feature which ensures notification data will not be duplicated even if a failure occurs during processing since it assigns Unique IDs for each pulishable document. If there is a processing failure, the IS checks for duplicate records in storage and ignores any of the duplicate IDs created during failure.

Stored procedure notification do not use publishable document unique IDs so they do not have support for exactly one notification feature.

Insert, Update and Delete Notifications use a combination of triggers and buffer tables to capture the events happen on specific tables in a dbase. While configuring the notification you configure the triggers and buffer tables. Adapter creates trigger and buffer table only when you enable a notification. The trigger monitors the table and inserts the data in buffer table and buffer tables holds the data.When you disable a notification adapter drops the trigger and corresponding buffer table.
Notification publishes the publishable document which contains a single row from buffer tables and after publishing the data/row is removed from buffer table.