The short answer is “No, they are not the same thing”
Many of OSHA’s safety standards for Construction and General Industry (e.g., 29 CFR
1910, Subpart S) require that equipment and products be tested and certified to help
ensure their safe use in the workplace. To implement these requirements, OSHA
established the Nationally Recognized Testing Laboratory (NRTL) Program and the
agency generally requires NRTLs to perform this testing and certification.
A NRTL functions to provide independent evaluation, testing, and certification of any electrically operated or gas and oil equipment. Underwriters Laboratories is one NRTL and perhaps the most well-known, but it is not not the only NRTL. You can find a complete list of NRTL’s here on OSHA’s website. For the remainder of this article, we will use “UL” as a designation that you can take to mean all NRTL’s.
The true legal requirement to test and certify products for sale in the US is a designation by OSHA by a Nationally Recognized Testing Laboratory (NRTL). Incidentally, the standard was just updated on 10/1/2019 and the new version can be found here
The letters "CE" are the abbreviation of the French phrase "Conformité Européene" which literally means "European Conformity" According to the European Commission website, CE Marking on a product states that the product is assessed before being placed on the market and meets EU safety, health and environmental protection requirements.
However, according to the website www.ul.com:
Unlike the UL Mark, the CE Marking
Is not a safety certification mark
Is generally based on self-declaration rather than third-party certification
Does not demonstrate compliance to North American safety standards or installation codes.
Both statements are true, but you, as the consumer or someone who specifies equipment, must understand that there are some competing priorities in play. First, the European Commission is interested in upholding EU regulations and as a government entity is not very interested in UL listing since that implies compliance with US safety requirements. Their goal is to promote trade between EU countries and ensure that the laws are complied with. On the other hand, Underwriters Laboratories is a “global independent safety science company” (their words not mine!) who have a stated goal of ensuring products are safe, and an unstated goal of making a profit. So, UL is of course going to say that CE marking is not equivalent and technically it is not.
Like most (or perhaps all) government programs, UL listing process is not a simple thing. After a manufacturer designs and builds a new piece of equipment, if the equipment requires or the manufacturer wants a UL listing, they first submit an application to the NRTL of their choice. The application has numerous requirements, some of which are:
A change control process such that all changes are documented
Certification that all equipment is produced using the same process as the equipment being listed.
Access by the NRTL to the factory with no advance notice
Provision(s) for permitting periodic factory surveillance
I have heard of construction projects where the owner buys and installs equipment that was manufactured in Europe and is CE marked but is not UL listed. The building inspector then required UL listing before providing the certificate of occupancy. This would clearly set the project back significantly in time and budget, so it is best to know upfront what will be required by the AHJ.