<< So they don't send you a retail kit when you RMA correct >>
You got it.
<< And the drive can be brand new or refurbished >>
Yup
A refurbished drive can be one that was repaired but usually they are items that were returned from the vendors because a customer returned it for refund thinking it was broken when their problem was something else. Maxtor (or whomever) tests the drive, finds it good and since they can't call it new, they use it for RMA's.