Three characteristics are used to describe a sound wave. These are wavelength, frequency, and amplitude. This is how high or low a sound seems. A bird makes a high pitch. A lion makes a low pitch.
Sounds also are different in how loud and how soft they are.
The intensity of a sound is the amount of energy it has. You hear intensity as loudness. Remember the amplitude, or height of a sound wave is a measure of the amount of energy in the wave. Pitch and loudness are two ways that sounds are different. Another way is in quality.