Difference between a grey import and AU stock for Mobiles/tablets?

AFAIK, if its a grey import, it is made in a weird corner of the world, and you get text in weird language when booting up the screen. Also, if the phone breaks, you'd have to send it to the store that sold it to you to get it fixed.

Are there any other differences? What about quality wise?

I'd like to hear from people who have a grey import and/or own both.

Thanks.