Egregore
To understand what an Egregore is you first need to understand what a Tulpa is
Tulpa Definition
Definition
Egregores don’t necessarily map onto humans. Rather than a hard-and-fast distinction, it’s more helpful to think of tulpas as a subtype of egregores, perhaps of the highest intensity.
Contextualising
Tulpa's map onto people while Egregores are persona's that can be mapped to just about anything.
This reminds me of how Yuval Noah Harari talks about the Animalist religions in Sapiens.