I have to do it for chemistry homework and I don't know the difference

Have you ever seen something glowing red or white when it is hot?

This would give you an indication, but then there's a theory for that too.

Planck's law - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Planck%27s_law)

As you can see in the graph, as the temperature gets higher, the wavelength gets shorter (on the horizontal axis) and in the electromagnetic spectrum, red is among the them waves with long wavelengths.

As more energy is given off, the wavelength decreases (you start getting orange, yellow, green, blue, etc) which mix to get white.