Both types of music grew out of oppression at different points in the history of Jamaica, each emphasizing a different approach to this oppression. Reggae carries an emphasized downbeat which ska emphasizes up-beats, usually with the use of horns. However, with the passing of time ska has come to carry messages of anti-racism, unity, and inclusion. The three waves of ska present very different themes and styles.
First wave is basically the original Jamaican music, with slow beats and mixed themes.
Second wave, or two tone, had it's birth in the United Kingdom in the mid 1970's and has a medium paced beat with messages of unity. Third wave ska, mainly and American phenomenon, is a mixture of ska with other types of music. 90.3 FM , an organization of Washington University. Problems go to the tech .