Kurtis are not something very unique anymore. It has become a wardrobe staple for Indian women as well as for women belonging to various parts of the world. While it is referred to as a tunic in other parts of the world, it is known as a Kurti in India mainly due to its resemblance to the Indian clothing for men, Kurta.
Jeans of the same size cut and color can fit one and the same woman differently, because there are just no two equal pairs of jeans. Besides, one should never forget that after you've been wearing jeans for some time they become larger, that is why you should probably buy jeans a bit smaller in size.