In PoN, the difference to me was much more clear.
Psukhe was passion made manifest, raw emotion somehow charged into the Real. The emotion itself is the meaning. No "thought, as it were".
Per Iyokus (IIRC) Anagogis is "passion become semantics, and semantics become real". Which is why they need an anchor like a sun or dragons to achieve the semantics (and desired result) of fire. Bringing an analogy to life. Like it was a single thread of thought achieving its results indirectly.
Gnosis (the most elaborated upon in the series, despite being the most "secret", which amuses me. But I digress) instead anchors the thoughts onto themselves. Two thoughts! Bracing each other's meaning. It's the duality of thought itself which seemed to be the secret that allows gnosis to achieve more abstract thought onto the onta. Or so I thought until the new series.
It's suggested now in TUC that all sorcery is rooted in this same duality of thought previously only attributed to the gnosis. And that's the driving mechanic that makes all of it work. If so, what is really the difference between the Anagogis and Gnosis? If the analogies are rooted in the same principles that make the gnosis work, how can it be so impossible for a human to ever have made what would amount to a slightly different application of it?
