Hi almuhtaseb, Sculpey is a company which makes several brands of general use oven cured (baked) polymer clay and also some specialty kinds of polymer clay. Sculpey III is their bottom line general use brand. Few serious clayers use it because is is very mushy to work with and even properly cured (baked), Sculpey tends to shatter. I highly recommend Sculpey's PREMO brand, a brand that many clayers here also use. This link to the company products that may help you understand some of their specialty clays. http://www.sculpey.com/product_category/clay-lines/
Not sure where you are located. If you are in the USA, most big box craft stores stock PREMO. If you are outside of the USA there are a number of reliable company's we might be able to recommend, depending on your location. I don't know of a source in India, though there may be one. The following is a link to a USA company that can ship to many countries, though clay is heavy and shipping is expensive. www.polymerclayexpress.com/ Then click on "clay"
In case you are a beginner, I have a generic post here at PCC that I love to share with new PC-ers that lists my hints, best beginner book, curing info, sites to get beginning info etc. Here is a link to the most recent time it was posted. It’s gotten so long that I’ve split it into two posts. So please check out both of my consecutive posts.
p.1 is basic PC info
p.2 is a list of URLs to PC resources including tutorials
You asked, " May u tell me what is the difference between air dray polemar and baked polymar? Which is better?"
We call one the generic name "air dry clay" (a general category name that would include a number of kinds and brands.) It isn't really used here much at PCC, or maybe not at all and the other "polymer clay" (which is what we use here at PCC and is oven cured (baked).) I imagine which one someone prefers is just a matter of personal preference and what they want use it for. Air dry clay seems to be used in Russia and Europe more than it is in the USA. There is one kind I think called cold porcelain.
"what is air dried clay and how it differs from PC"
PCD including flowers; various artists utilizing medium
Different air dry brands explained
Anita in AZ