African American hair is the same in composition as Caucasian and Asian hair, but the way the wave patterns form can make it very vulnerable to breakage. There is no one specific wave pattern or growth pattern for African American hair, just like there are many variations for Caucasian or Asian hair. But it does tend to grow more slowly and need more moisture than other types of hair. Textures can range from very kinky to smooth, it all depends on genetics. How you care for your hair is more important than what the texture may be, and with proper care African American hair can be very beautiful.
If you use a relaxer this increases the chances of breakage even more.