Standards Explained - ISO 45001-2018

BS OHSAS 18001 has now been replaced by ISO 45001:2018
ISO 45001:2018 specifies requirements for an occupational health and safety (OH&S) management system, and gives guidance for its use, to enable organizations to provide safe and healthy workplaces by preventing work-related injury and ill health, as well as by proactively improving its OH&S performance.

ISO 45001:2018 is applicable to any organization that wishes to establish, implement and maintain an OH&S management system to improve occupational health and safety, eliminate hazards and minimize OH&S risks (including system deficiencies), take advantage of OH&S opportunities, and address OH&S management system nonconformities associated with its activities.

ISO 45001:2018 helps an organization to achieve the intended outcomes of its OH&S management system. Consistent with the organization's OH&S policy, the intended outcomes of an OH&S management system include:

a) continual improvement of OH&S performance;
b) fulfillment of legal requirements and other requirements;

c) achievement of OH&S objectives.

ISO 45001:2018 is applicable to any organization regardless of its size, type and activities. It is applicable to the OH&S risks under the organization's control, taking into account factors such as the context in which the organization operates and the needs and expectations of its workers and other interested parties.

ISO 45001:2018 does not state specific criteria for OH&S performance, nor is it prescriptive about the design of an OH&S management system.

ISO 45001:2018 enables an organization, through its OH&S management system, to integrate other aspects of health and safety, such as worker wellness/well being &working enviroment.

ISO 45001:2018 does not address issues such as product safety, property damage or environmental impacts, beyond the risks to workers and other relevant interested parties.

ISO 45001:2018 can be used in whole or in part to systematically improve occupational health and safety management. However, claims of conformity to this document are not acceptable unless all its requirements are incorporated into an organization's OH&S management system and fulfilled without exclusion.

To sum it up
OHSAS 108001:2007 – BS OHSAS18001 Occupational Health & safety Assessment Series was a British Standard and NOT an ISO standard
OHSAS 18001:2007 – BS OHSAS18001 was replaced by ISO 45001:2018 in March 2018
ISO 45001:2018 (OHS) Occupational Health and Safety (Management System) is the first global system

The differences between are
ISO 45001 is process based OHSAS is procedure based
ISO 45001 is dynamic in all its clauses, whereas 18001 is not
ISO 45001 considers both risk & opportunity whereas 18001 only considers risk
ISO 45001 includes views of interested parties, 18001 does not
ISO 45001 common framework ISO 9001 & 14001
The objective is by 2022 all organizations will have have changed to ISO 45001 - 2018