https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_for_houdini_6330_html

• Arnold for Houdini (or HtoA) provides a tight bridge to the Arnold renderer from within the standard Houdini interface, in a way that is familiar to both Houdini users and Arnold users in Maya or Softimage. It also enables smooth lighting workflows between Houdini and other DCC applications, since setups can be exported and shared.