Hi Priyanka,
I think Venkatesh has well defined the concept.
But i also would like to add some more examples as requested by you. Let me know if it helps you in any ways.
Reference Date is the DATE on which PWS starts.
Starting point is POSITION of PWS at which reference date is set.
These two points are the part of Work Schedule Rule (WSR).
Below mentioned print screen is for your reference.
Under WSR when we select particular PWS and select 01012015 as REFERENCE DATE for that PWS and 001 (MONDAY a PWS, here 001-Mon, 002--Tues, etc) as STARTING POINT for the very same PWS
This particular group of EEs are requested to start their shift/DWS (9X80 in below print screen) on 01012015 which is Monday.
You may press F1 to read more about Reference date and starting point. There are good examples explained for your knowledge.
regards,
Amit