I think it's because the way they were released. The 10.5 shares pretty much everything other than screen size with the second gen 12.9. So while there's only one generation of iPad Pro 10.5, there are two gens of iPad Pros in general and the 10.5 uses the second generation of hardware.
At least, that's the best I can come up with that makes sense, but yes, they're definitely talking about the 10.5 that you have.