What are the difference between Notify url and Return url?
PayPal | Notify url and Return url
Both of these are used in PayPal payment gateway integration.
Notify url is used by paypal to send response regarding current transaction in other word notify about the current transaction done in your site.
<input type="hidden" name="notify_url" value="https://www.yoursite.com/your_ipn.php">
By paypal: “Instant Payment Notification (IPN) is a message service that automatically notifies merchants of events related to PayPal transactions.”
Return url is use to specify the returning url after current transaction done. It is a redirect page url which is specified by the developer. Something link a page having "Thank you for your payment" message.
<input type="hidden" name="return" value="https://www.yoursite.com/checkout_complete.php">