Not sure about those specifically, but I always thought Global Wests Del-A-Lum material was what set it apart. How would you know that the Ebay one uses the same stuff?
I would make sure that what is in the picture is the real part. Ask to make sure it's not a "stock" picture. I have seen a set of the knock off's in person and other than they are heavier than stock control arm the welds "look" ok not any worse than some I've seen on top brands. But you really don't know what they are made from as far as materials go. For a driver just looking to have the tubular control arm they will work, but have heard some compalin that they couldn't get it to aline very good.