Dear Venu
Seems that there are certain transactions where goods delivery is adone but Invoicing not done. As you have done invoicing for 13500 only so you are accepting it. Check pending Invoicing status then you will come to know that there are still pending amount.
You are looking at only your invoicing entries but the other accounts are hitting at the time of Goods delivery. So you have done delivery of 331000 but only billed 13500. This 669000 is your FG inventory account balance.
Regards
Rajneesh