The "Agreement to Sell", "Agreement for Sale" and "Agreement of Sale" are synonymous terms. The agreement of Sale is a simple agreement which lays down pre conditions to the sale of a immovable property. However, title does not pass with the agreement for sale, and the Purchaser (Under an Agreemennt to sell) does not become the owner of the property unless and until a Sale Deed is executed in his favour,
Section 54 of the Transfer of Property Act defines the Contract of Sale or An Agreement to Sell in the following words: " A contract for the sale of immoveable property is a contract that a sale of such property shall take place on terms settled between the parties.It does not, of itself, create any interest in or charge on such property."
Therefore, getting the Sale Deed Executed is a must, for the Tranfer of Property.
Should you require any further assistance, do revert.