Purchase agreement has details about the purchase made by the buyer. We can also say that purchase agreement has the details about sale so made by the seller. It is basically a document creating rights and liabilities of parties to the agreement.
Purchase agreement has the purchasing price, the particulars about the product so purchased, the particulars of seller, the particulars of purchaser, date of purchase, date of delivery of product, rights and liabilities of parties and other similar things mentioned on it.