Shenu ring protects the Energy of the God.
The Solomonic circle is meant to "protect" the summoner from the God as they're summoning them in a hostile fashion using Hebrew names to "command" the entity.
What I think is going on here is that the ritual produces an imagination for the practicioner who sees a “Demon” in the form described in the Lesser Key.
Several Hebrew names are chanted before the “Demon” is summoned. The 4 Archangels (representing the 4 directions and 4 material elements) are also invoked before the names of “God” are used to “command” the Demon. It’s all described in detail in the book. The circle more than likely keeps the Demonic energy away from the magician while the magician immerses themselves with hebrew energies.
The energy invoked is like 99% hebrew and the Demonic name is usually corrupted by a hebrew renaming. No real Demonic/Divine Energy ever interacts with the enemy practioner, or the very little that does is swamped with hebrew energies, thus making any communication attempt futile.
Many have reported their lives being ruined from such practices or nothing being done for them.
In contrast the Shenu ring is used to protect the Energy of the God that we empower and bring more down of in this realm from enemy attacks.
Unlike the enemy practioner who drowns themselves in hebrew, we immerse ourselves in Divine Energies.
The Shenu Ring helps protect that Energy. The Binding circle keeps that energy away from the enemy practioner.
For jews this likely protects them somewhat from attacks by our Gods. Although books like the “Lesser Key of Solomon” are largely Gentile LARPs of jewish kabbalah that rabbis would never use. It’s mainly enemy Gentile occultists still trapped in enemy paradigms who use these things.
For Gentiles it helps keep them under the influence of the hebrew energies/entities who wouldn’t want Divine Energies putting any rebellious ideas into their shabbos goy servant. The Gentile practioner will as a result suffer from deception, tragedies and who know what else from the enemy who trolls them. Some have been killed from “summoning Demons”. This has never happened with us so whoever was killing them wasn’t our Gods, instead it was the hebrew shit they were smoking.
While both are circular, the Shenu ring and the binding circle serve very different purposes.