Unstitched products are fabric materials which can be stitched by the customer to your exact size.
Semi-stitched products come half-stitched. For example, semi-stitched lehengas have a blouse material but the skirt is half-stitched. So, you will have to tailor it to your size.
Readymade products are ready to wear according to pre-set sizes like S, M L, XL etc.