how does DISTINCT work in SQL, i mean how does it internally works if i im using it for 2 column in same table!!!!please asap

how does DISTINCT work in SQL, i mean how does it internally works if i im
using it for 2 column in same table!!!!please asap

how does DISTINCT work in SQL, i mean how does it internally works if i im
using it for 2 column in same table!!! lets say im using the scott user,
and in that if im querying like SQL> SELECT DISTINCT Deptno, Job FROM EMP;
AND SQL> SELECT DISTINCT Job, Deptno FROM EMP; Then Ans Have The Same
Values But Their Order Is Not Same For The Two Queries...... I Want To
Know Why Is The Difference In The Output..... And How Is It Internally
Executing The 2 Queries... Im New To Sql Please Help Me Build My
Concepts.. Thanks....