Final answer:
Primary fuels are used in their original form for energy consumption, while secondary fuels are derived from primary fuels through conversion processes, such as generating electricity.
Step-by-step explanation:
Primary and secondary fuels are terms used in energy consumption and conversion. Primary fuels refer to fossil fuels in their original form, which can be directly used for transportation, heating, or electricity generation. For example, coal and natural gas are primary fuels when used for heating.
On the other hand, secondary fuels are those derived from primary fuels through conversion processes. A common example is electricity, which is generated from primary fuels like coal or natural gas in power plants. This electricity is then used for various purposes, such as operating appliances or charging electric vehicles.
So, the main difference between primary and secondary fuels lies in their original form and how they are utilized. Primary fuels are directly consumed, while secondary fuels are the result of converting primary fuels into other usable forms, typically electricity.