HRV recovers only heat, using a metal or plastic core.
ERV recovers heat and moisture using a membrane core.
HRV are more efficient at recovering heat then ERV as the core has more surface area and better conductivity.
Which to use depends on your climate, building use, occupancy, how many plants in the house and other factors:
Cold and dry or hot and humid climate most often an ERV.
HRV most other times.