Unsubscribing at PayPal when using PayPal standard just cancels the recurring payment so they won't be billed again. It'll completely deactivate when they expire or if the use Unsubscribe a second time to get rid of the actual subscription on-site (note they won't be re-billed if unsubscribed at PayPal). PayPal Pro is all internal, automated, with no PayPal account needed so it cancels it all. As far as I am aware PayPal Standard is the only gateway that does this.