The first difference concerns its structure. Some of the main differences between the two standards are explored below. The experts at The Registrar Company took the time to dissect the new standard to determine the most pertinent differences between the two standards that you need to know. A number of differences are evident between ISO 45001 and OHSAS 18001. ISO 45001 is an OH SMS standard developed by an ISO Project Committee which was published on March 12th 2018. 19 years later, a new ISO standard has been released to replace OHSAS 18001 this standard is ISO 45001. Since its first publication in 1999, OHSAS 18001 has been a recognized occupational health and safety management system (OH & SMS) standard against which management systems can be assessed and certified.