Can we further classify the roles?

"Tank" is pretty non-descriptive. The new "Juggernaught" division helps but even in the remaining CC-heavy tanks there are further nuances to their play-styles and how they best approach a game.

You have Engage Tanks like Amumu or Malphite who are extraordinarily good at reaching the enemy and/or locking down multiple people

You have Peel Tanks like Alistar and Maokai that are better at defending their team with localized CC, shorter ranges and defensive utility.