Total sugar includes the sugars already in the ingredients and any added sugar. The added sugar row tells you how much of the total was added. Use both rows on the same serving basis.
Try a sample pack
Imagine a flavoured curd label that lists 12 g of total sugar and 6 g of added sugar per 100 g. The 6 g is already included in the 12 g. If you eat the full 150 g cup, that comes to 18 g of total sugar, of which 9 g is added. These are made-up numbers to show the maths.
Compare on the same basis at the shop
If one pack shows figures per serving and another shows them per 100 g, first convert both to the same weight. Then look at how much you plan to eat. Read what “no added sugar” means · FSSAI’s label reference
Whole fruit or juice? Compare an orange with a glass
Try the same check on two packs
Pick two flavoured curds or two breakfast cereals you might actually buy. Write the total and added sugar side by side on the same weight basis. If you usually finish the whole cup or packet, work out the sugar for the full pack next. This way you can compare the amount you would eat even when the packs print different serving sizes on the front.