As per my knowledge, the subject of Organizational Development deals with the appropriate application of tools based on the analysis or survey of organizational diagnosis. This is done through sample questionnaires and feedback from members of the organizations. After thorough analysis, proper proven tools (interventions, OD Intervention) are applied to resolve the issues, and the effectiveness of the intervention is measured through continuous monitoring.
On the other hand, HRD as a Total Function
HRD is a total function that helps to integrate human resources, develop, evaluate performance, etc., upon which the success of the organization depends. I think both are important; however, if the effectiveness of HRD functions is achieved on a large scale, the need for OD is reduced.
Regards, Vipul Rana