Consider that Adata does not make harddrives; WD does.
You'll know you have a WD drive in your WD external. You have no idea what will be in the Adata and its likely to be the cheapest drive they could source at the time; kind of like the way all bids work.
AS for the advice, lonewolf is right. external drives tend to fail more for a variety of reasons. The very enclosure tends to trap heat and the hotter a drive runs the sooner it will fail. External drives get moved, carried, and eventually dropped. Sure a rubberized housing helps but your still applying an impact to the mechanical drive.
IMO external drives are for moving copies of data and should never be used to store the only copy. Just look thru our fourms and see how many...