The biggest difference between UL and CE is UL does not include EMC type testing where CE marking a product almost always does. This is to prove that the device will not malfunction when exposed to radiated or conducted emissions from other equipment. In addition, it had to be tested to make sure it is not radiating any trash. The combination of UL and the FCC requirements are more closely compared with CE marking more so than UL by itself. Another notable mention is that UL marking a product is not mandatory where as CE marking is a requirement to sell to the EU. Also, condsider CSA marking. This is similar to UL marking only for mostly canada but some companies are requiring this in the US. The mark required varies from customer to customer. Hope this helps. Buzz