Preventive Action (9001:2008 Clause 8.5.3) has been removed in 9001:2015.
Clause 6.1 (Actions to address risks and opportunities) is being used to replace 8.5.3. This coincides with section 0.5 “Risk-based Thinking” and appendix A.4 “Risk-based approach”.
A.4 states “This International Standard requires the organization to understand its context (see clause 4.1) and determine the risks and opportunities that need to be addressed…. One of the key purposes of a quality management system is to act as a preventive tool.”
There should not be any differences for how corrective actions or improvements are made or documented.