Both Zydeco and Cajun are two different types of music, and most times people tend to use both music styles for each other, probably because the two are a bit related in terms of origins. Nevertheless, there are some differences between Zydeco and Cajun, and those differences are basically on how the two styles of music are played and the types of instruments used when playing the two songs. Zydeco is a brand of music which belongs to the black creoles of southern Louisiana. This music is majorly played with one special single chord and the rhythm too is very unique in terms of how it is played, most times characterized by returning rhythms that are constantly played together with the music.
Different instruments used for zydeco music are majorly wind instruments and sometimes washboard. Cajun, on the other hand, is also a brand of music which belongs to the white Cajuns of southern Louisiana. This type of music sounds more like jazz and waltz types of music, and it is played by constantly repeating some notes which is definitely the unique hallmark of the music style. Different instruments used for Cajun are fiddle and accordion and others.