There are 10 different types of Anomaly Class Class 1 (easiest)-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)

** Damage types ***
Guristas - Kin/Ther (weak vs Kin)
Serpentis - Therm/Kin (weak vs Therm)
Blood Raider - Therm/EM (weak vs EM)
Sansha's Nation - EM/Therm (weak vs EM)
Angel Cartel - Kin/Expl/Therm (weak vs Expl)
Mordus Legion - Therm/Kin
Minmatar Fleet - Therm/Expl
Amarr Navy - EM/Therm
Thukker Tribe - Therm/Expl