What is the difference between CoQ10 and CoQ?

Could you please clarify the distinction between CoQ10 and CoQ? Are they variants of the same compound, or do they have distinct properties and functions? It seems that CoQ10 is frequently mentioned in the context of health supplements and antioxidant properties, while CoQ is less commonly discussed. Is there a specific reason for this disparity in popularity, or are they simply different names for the same thing? Additionally, are there any notable differences in their biological effects or potential applications?