Is ONT and ONU the same?

Excuse me, could you clarify something for me? I've been hearing about both ONT and ONU in the context of cryptocurrency and finance, but I'm not entirely sure if they're the same thing or if they serve different purposes. Could you please explain the difference between ONT and ONU, if there is any? I'm particularly interested in understanding their unique features and how they fit into the broader cryptocurrency landscape. Thank you in advance for your help.