Subtracting Dates in Oracle - Number or Interval Datatype?

Question

I have a question about some of the internal workings for the Oracle DATE and INTERVAL datatypes. According to the Oracle 11.2 SQL Reference, when you subtract 2 DATE dataty

Answer 1

select TIMEDIFF (STR_TO_DATE('07:15 PM', '%h:%i %p') , STR_TO_DATE('9:58 AM', '%h:%i %p'))