Speed metal
Speed metal eventually evolved into thrash metal. Although many tend to equate the two subgenres, there is a distinct difference between them. In his book Sound of the Beast: The Complete Headbanging History of Heavy Metal, Ian Christe states that "...thrash metal relies more on long, wrenching rhythmic breaks, while speed metal... is a cleaner and more musically intricate subcategory, still loyal to the dueling melodies of classic metal."