Pre-Approval
A loosely used term which is generally taken to mean that a borrower has completed a loan application and provided debt, income, and savings documentation which an underwriter has reviewed and approved. A pre-approval is usually done at a certain loan amount and making assumptions about what the interest rate will actually be at the time the loan is actually made, as well as estimates for the amount that will be paid for property taxes, insurance and others. A pre-approval applies only to the borrower. Once a property is chosen, it must also meet the underwriting guidelines of the lender. Contrast with pre-qualification.

Purchase Agreement
A written contract signed by the buyer and seller stating the terms and conditions under which a property will be sold.

Source: The Canadian Real-Estate Association (http://www.crea.ca)