The slight difference in address could be one is work and the other is home.
If they paid with PayPal, you should have their email address too, which you could try sending a message that way.
In your situation, i'd nudge the message twice, and after a week if no response, either send item to PayPal registered address (that way you're covered if they say it didn't arrive), or cancel the sale and loose out on the fee's you've incured from the payment.
Of course it all depends on the value of what you're sending, and whether it's recorded shipping or not.
Jason