Within our Aviation system both Quality and Safety Management systems have shared common values. To be effective they both have to be planned and managed and provided with appropriate resources. In addition both aim to involve every relevant functional element within the organization and indeed, both processes strive for continuous improvement. 

Root Cause is Root Cause you may correctly say! So how can there be a difference between Quality Management Systems (QMS) Root Cause and Safety Management Systems (SMS) Root Cause.

Lets first consider the Different roles of Quality & Safety.

Quality is looking at Compliance (It has happened!).

Quality systems tend not to consider the role of risk whereas of course this is a fundamental tenant of the SMS system.

The Quality Management System (QMS) remains however the primary means of ensuring that the organization is meeting requirements (Ensuring Regulatory Compliance) and continuously improving its processes.