Final answer:
The primary distinction between thermal energy transfer through radiation and conduction/convection is that radiation relies on electromagnetic waves and can occur in a vacuum, while conduction and convection require a medium.
Step-by-step explanation:
The primary distinction between thermal energy transfer through radiation and conduction/convection is that radiation relies on electromagnetic waves and can occur in a vacuum, while conduction and convection require a medium. In other words, radiation can transfer heat through empty space, such as the heat from the Sun reaching the Earth. On the other hand, conduction and convection require the presence of matter to transfer heat, such as the heat transfer from a burner of a stove to a pan through direct contact (conduction) or the movement of fluid to transfer heat (convection).