There are 10 different types of Anomaly Class ranging from Class 1 (easiest) to Class 10 (hardest).
Class 1 = (Faction) Hideaway or Drone Cluster (easiest) Class 2 = (Faction) Burrow or Drone Collection Class 3 = (Faction) Refuge or Drone Assembly Class 4 = (Faction) Den or Drone Gathering Class 5 = (Faction) Yard or Drone Surveillance Class 6 = (Faction) Rally Point or Drone Menagerie Class 7 = (Faction) Port or Drone Herd Class 8 = (Faction) Hub or Drone Squad Class 9 = (Faction) Haven or Drone Patrol Class 10 = (Faction) Sanctum or Drone Horde (hardest)
Each Anomaly Class has 4 different levels, ranging from Level 1 (easiest) to Level 4 (hardest).