what kind of question is this
A beginner/student question
It is extremely important to use proper terminology as well as clearly state your requirement or doubt. . .
Tables have rows not records.
select * from emp where emp_id=19 returns 10 records
Nearly always emp_id is the key to the table - why are there 10 emp rows with the same id? Is this a complete typo? Is dept_id really what is needed?
Are you trying to understand why the 2 queries return a different number of rows or are you trying to have the query return the value obtained by calculating the difference in the number of rows returned?