I don't think they're really the same. My 11" IPP has support for the better Apple Pencil 2 with a superior charging/pairing system, a great Smart Keyboard Folio, the design is so much more better than the air (I love the squared/flat edges), I have 512GB of storage, USB-C support, ProMotion, rounded corners look elegant, better camera WITH flash with support for portrait mode/animojis, 2 additional speakers, and FaceID (it's so much better than Touch ID and you won't change my mind).
They're very different devices and the "Pro" designation shows that it's more powerful and not really in league with the regular models including the air. I love my 11" and I don't see me getting rid of it anytime soon. I'm actually getting rid of my 12" Macbook because I'm not using it anymore. lol
The only thing is sometimes I regret not getting the bigger 12.9 iPP. Lol