Proton Pass is a password manager designed to securely generate and store strong passwords, and protect your digital identity with features like email alises and dark web monitoring. It also includes an integrated authenticator that can store and autofill 2FA codes - but not the ones used to log in to your Proton account. Proton Authenticator is a standalone 2FA app that allows users to enable 2FA protection for their Proton account, it also allows users to store their 2FA codes separate from their passwords if they wish to do so.

Seems like basically an ad platform/gateway to Pass.