While the term Grindcore has often been used somewhat interchangeably with death metal, the two started out as very different, albeit similarly extreme, forms of music, despite becoming more alike over the years. When it first appeared in the mid-'80s, grindcore in its purest form consisted of short, apocalyptic blasts of noise played on standard heavy metal instrumentation (distorted guitar, bass, drums). Although grindcore wasn't just randomly improvised, it certainly didn't follow conventional structure, either; while riffs could sometimes be picked out, pure grindcore never featured verses, choruses, or even melodies. Grindcore vocals sounded torturous, ranging from high-pitched shrieks to low, throat-shredding growls and barks; although the lyrics were usually quite verbose, they were very rarely intelligible. Grindcore's jaw-dropping aggression was so over the top that pointing to its roots in thrash metal and hardcore punk hardly gives an idea of what it actually sounds like. Indisputably, the band that invented grindcore was Napalm Death, whose 1987 debut album Scum is also perhaps the most representative example of the style.
http://www.ranker.com/list/the-all-time-best-of-grindcore/revconradhutchings,
Bleeding Through
Brutal Truth
Carcass
Cattle Decapitation
Dagoba
Job for a Cowboy
Napalm Death
Pig Destroyer
As I Lay Dying
Atrocity