Differentiate Admin and Moderator Shield Icons

Nope, it’s for any user who has enable 2FA within Discourse (staff or not).

In the image above you can see 3 users - one is an admin with 2FA enabled, one is an admin (bot), and I am an moderator & admin and have 2FA enabled. See Discourse 2.0.0.beta4 Release Notes for more details on 2FA in Discourse.