shipping option not showing up as listed in the shipping policy

[peakviewz]

so, i have a shipping policy that offers 3 different ways to ship the item for variety on large or heavy items.  One option listed in the policy was USPS retail ground, which was available to list as a shipping type in ebay when i was creating it.  Now that they bought the item and selected USPS retail ground... I go to print the shippin label and nothing in the option of shipping for me to select says ' usps retail ground'  why is it offered in one area of ebay but not actually there when the shipping occurs.  Is there a title change i am not seeing?  is usps retail ground mean i have to physically go into the post office and wait in line for postage?  the option of USPS Parcel Select seams the same price but a few cents cheaper actually.  is it the same? what is the difference and why doesn't ebay list both in the option to select?  

[partial*eclipse · Accepted solution]

Yes, Retail Ground and Parcel Select Ground are essentially the same service.  Both used to be known as Parcel Post.  And Retail Ground can only be purchased at retail, i.e., at the Post Office counter.

For packages that are not over 18 pounds and not over 1 cubic foot, the online price for Priority Mail will be  the same as for Parcel Select Ground, or just 5 cents more.