What is the difference between a boiler operator and a boiler engineer?

There is little difference between a boiler operator and a boiler engineer. Some use the same title interchangeably; others just use "stationary engineer" to refer to the same role. The main difference in title is what is listed on formal certification and licensing. Boiler engineers may indicate a level of certification has been passed, and those who carry this title will often train or mentor rising boiler operators. Different trade unions and states refer to the same role by different names, so boiler operators, boiler engineers, and stationary engineers may all refer the same type of job.