Here's a breakdown:

* Cool stars are classified as having a surface temperature between 3,500 and 5,500 Kelvin.

* Orange stars have a surface temperature between 4,000 and 5,000 Kelvin.

* Red stars have a surface temperature between 3,500 and 4,000 Kelvin.

While "red" might be the most common term, some orange stars, particularly those closer to the red end of the spectrum, can appear to be more orange than red to the human eye.