As standard the API returns the full address fields: Address lines 1-6, Town, County and Eircode.
However, it can return any fields as contained within the Royal Mail PAF or Eircode ECAD data file. For example, with Irish addresses the following fields can also be returned:
ECAD ID
Administrative / Boundary Information (Small Area Boundaries, Electoral District boundaries etc)
Geo Spatial Information such as XY coordinates.