It's for the professional installer, as in a mechanic shop. It's a way to get a cheaper part but sell it to the customer as a "Genuine AC Delco" part. I wouldn't say they're "low-grade", but they tend to be "lower-grade". The "Advantage" line is the cheap shit. It's advantageous for the shop and customer to have the cheapest cost part but not feel bad about it cuz it's "AC Delco".
It seems that AC Delco uses the better aftermarket parts for their Professional line. For example, my AC Delco Professional upper and lower control arms were re-boxed Moog CK series. There are plenty of other examples of this, such as with the hub bearings.
Speaking of all this "Professional" line stuff.
I wasn't happy with the Strongarm brand of liftgate struts that I installed back in December on the Burb.
When it was cold out the power liftgate would get almost all the way to the top/fully open, and then would reverse and start coming back down as though it had encountered an obstacle.
I didn't notice this immediately as we don't get a ton of "cold" weather. My point is by the time I realized this I had already thrown out the original lift struts. There wasn't really anything wrong with the old ones, I replaced them as PM thinking it would make the liftgate motor's life a little easier having new struts to lift it.
Anyway, my point in saying all of this is that I went on RA and bought the only AC Delco lift struts they carry, which is the Professional line.
They came in yesterday and guess what...
They are the same exact "Strongarm" lift struts that I currently have on there. Same exact sticker, part number, everything.
I installed the new ones anyway just incase I got a bad one the first go around.
I put the Strongarms back into the AC Delco sleeves and I am sending them back for a refund. The Strongarms were about $15 each and the rebranded Delcos were about $25 each.
Heck of a racket they have going... lol