If you have certification to OHSAS 18001 you will need to migrate to ISO 45001 to maintain the validity of certification. There is the normal 3 year migration period so there is still time to plan your move over to ISO 45001.
New terms and definitions in ISO 45001
The new definitions of the terms 'Risk', 'The Worker', 'The Workplace' and 'Hazard Identification' may change for the following reasons:
Risk. A universal definition of the term 'Risk' is clarified in ISO 45001 as the meaning of this varies in some countries. The term 'Hazard Identification' is covered by the terms 'risk identification and 'risk control' to ensure we encompass all potential hazards applicable to all industries and sectors.
The Worker. There are differences in the definition of this term and various legal constraints around this term in different countries -- in the context of ISO 45001, 'The Worker' is defined as the person working under the control of the organisation and includes subcontractors.
The Work Place. There are questions amongst organisations regarding what the workplace is, is it your organisation's site?
Preparing For The Future
Charles Corrie's recommendations to adopters and non-users of OHSAS 18001 health and safety management systems: "existing users, don't panic!"
Many clauses requirements of ISO 45001 are the same or similar to OHSAS 18001 -- however they are presented in a different sequence and may use different terminology.