Clarification Needed on Course Icon Color Coding

Hello Khan Academy Community,

I've encountered a curiosity within the course listings that I hope someone could clarify. Some courses are marked with blue icons, while others have yellow icons with mathematical symbols. I've looked through FAQs and searched the forums but haven't found an explanation for the color distinction.

Does anyone know what these different colored icons represent? Is it related to the type of course, level of difficulty, or something else? Any information or direction to an official resource on this matter would be greatly appreciated.

Thank you!