All of those marks mean exactly the same thing - that the Nationally Recognized Test Lab that has evaluated the product finds it to be in compliance with the applicable safety standard. What is confusing (to people who don't know) is that any of those marks could indicate that a product is, for example, listed to UL 467 or to a CSA standard, etc. The term "UL" is used like we used to use "Xerox" for copier or "kleenex" when we mean tissue paper. This is because UL is huge in the United States and writes a lot of the safety standards that all NRTLs use. So "UL 467 compliant" means the product complies with standard UL 467, but may have been evaluated by any NRTL, not necessarily Underwriters Laboratories.
The validity of marks can sometimes be verified easily (though you may still have a counterfit product, in which case the mark is invalid because the manufacturer and manufacturing location will not match with what is written in the safety report and the fraudulent manufacturer will not be subject to quarterly factory inspections like the real manufacturer is)
To check on a product bearing the UL or UR mark:
Go to www.ul.com
Select "certifications" from the collumn on the left
Select "company name/location" or "UL file number". Use "file number" if the UL mark you are verifying has a Exxxxxx number next to it. Use "company name" if you want to see everything the company in question has a file for.
Searching for "Halex" (for example)you will find two pages of product classifications. Select one and you will see all the model numbers of a product category verified to meet a certain safety standard.
click on "guide information" to see exactly what that standard covers.
To verify or check for ETL marks, go to www.etlsemko.com
and click on "product directories" in the upper right side of the page. Its self explanatory after that - you can search by the ETL control number or by company name.
Some marks are difficult or impossible to verify online. Others, like the CE mark, are not associated with tests done by certified labs and are self-regulated and need to be verified directly with the manufacturer (the CE simply means the manufacturer states the product is in compliance with applicable electrical safety and EMC standards for the European Union.)