Hello jyoti,
All have rightly mentioned that what prime purposed of loop control are and what for you should use it. As far as your query is concerned , there could be various reasons why your two results are varying. I suggest you to first set alike parameters for every component you are using in your system design. Also try to disable the ‘generate seed’ option. logically , the results should not vary much. I hope you implement all these things and check for the results.
Regards