I had a brand new Moto X (2nd Gen). I was troubleshooting a problem and, during what was then the 30-day return window, replaced it with my Moto X (1st Gen) during the troubleshooting. That replacement automatically initiated the return process. That was a bit of a headache since I actually didn’t want to return the phone.
When the 3.0 phones came out I purchased a Moto G+ just for testing. On the 13th day I reactivated my Moto X (2nd Gen) as a replacement for it and within minutes received the email with the return label. Shipping was FedEx SurePost and that phone was picked up at my mailbox right away but took at least 10 or 12 days to reach RW. They inspected it in short order (3 days as I recall) and the credit was applied to my account about 5 days after the inspection so it took about 20 days to get my money back.
There is a big difference between returning a phone under the terms of their satisfaction guarantee/return privilege and replacing a phone that develops a problem shortly after activation. In one situation you get a refund, in the other you get a replacement phone. This is why you see a difference in the procedures.