Is there any conceptual difference between a
SERIALIZABLE Transaction and a Flashback Query?
They are completely unrelated concepts.
- Serializable is a type of isolation level (read here for more info)
- Flashback Query is an Oracle technology for getting querying data as it was at a certain point in time - for example, if certain conditions are met you can use Flashback Query to get those million rows back after committing that transaction that accidentally deleted them.