Yeah, those are the middle of the road motors. There's GM OE/OEM, ACD professional gold, and ACD professional silver. IIRC, those you ordered are Professional Golds under GM p/n 19251414. Meaning they are expected to be made to GM specs, usually- but not always- by a non-GM provider. It could very well be a re-labeled, re-boxed aftermarket that's been checked by ACD to match or at least come close to GM specs.
While I always strive to get GM OEM, if I can't, the ACD professional will work fine for stock parts, IMO. It could also be a case of the professional series motor is the exact same across the board in quality, and just put a different part number on it. It's hard to tell unless you worked in the facility.
The silver series is your cheapest option, and they're still backed by GM, but in the "value" line. Take it for what it's worth.