These are the main ones for me:
─Session can mirror one identity across devices; Keet ties a room to a single device keypair.
─Session’s open groups or community servers provide moderation and persistence; Keet rooms vanish when all peers leave.
─Session’s design hides IPs behind onion-routed relays; Keet peers still expose IPs directly.
In short, Keet has the true p2p spirit, but Session has the usable infrastructure.
And I seek a balance between extreme privacy that is not useful, with acceptable functional privacy.