Sure! End-to-end encryption (E2EE) in a messaging context is about the service provider (Meta for WhatsApp, Apple for iMessage) not learning the contents of messages sent on the platform. E2EE also gets used when referring to backups, where it again refers to the service provider of the backups not learning the contents of backups.

Private retrieval is a more general concept, which refers to retrieving data from a server without letting it learn your access pattern. In a specific application, it's easier to see the contrast: for example, in our password checker (https://playground.blyss.dev/passwords), the data that Blyss helps keep encrypted, and prevents the server from learning, is which password you are checking. With standard E2EE techniques, it would not really possible to keep your query private.

In messaging, Blyss can be used to build messaging services that not only do not learn what you say (the standard E2EE guarantee), but also do not learn who you talk to. We're working on this, but it's a tricky thing to ship.