Dear Niki,
I got to this thing from one of my friend.... Look, there are two things -
1) "Agreement to sell" - This is made on stamp paper, but stamp duty is not paid at tthis point, On the basis of this seller accepts "earnest money" from the buyer. It's like a booking amount but this is not mandatory in every situation this is entered when there is some gap between initial booking & actual sale/purchase of property.....
2) "Sale agreement" - This is also made on stamp paper, & stamp duty is to be paid, stamp duty is paid at a percentage (say 8%)on "circle rates" which r fixed by the local authorities having regard to a particular area/colony, etc..This rate of stamp duty is generally less for women.