Two words that were used interchangeably for about three years and then separated permanently, and the separation happened because of a geographical accident rather than a musical argument.
The short version: speed metal kept the singing and the melody and went to Germany. Thrash abandoned both and stayed in California. What follows is the longer version, with the actual criteria.
Where the confusion comes from
Between roughly 1983 and 1986, both phrases described the same records. Press coverage used speed metal for Metallica, Slayer, Exciter and Anvil without distinction, and the bands themselves used neither consistently.
What forced the split was that a genuinely different music appeared in Europe using the same tempos. Once Helloween and their successors existed, a listener needed a way to say fast and melodic as opposed to fast and hostile, and speed metal drifted to the first while thrash took the second.
The four differences
The vocal is the loudest signal. Speed metal has a singer, often with real range, hitting notes deliberately. Thrash has a shouter, and pitch is incidental to what the voice is doing.
The riff is the second. Speed metal riffs are melodic and often built on major or harmonic minor shapes that resolve pleasantly. Thrash riffs are chromatic and percussive and frequently refuse to resolve at all.
The lead playing is the third. Speed metal solos are composed, melodic and neoclassically inclined. Thrash solos are, with honourable exceptions, atonal events that exist to raise the temperature.
And the subject matter is the fourth. Speed metal writes about heroism, mythology and flight. Thrash writes about the arms race, addiction and institutions.
The bands that sit in between
Every taxonomy has awkward cases and this one has several worth naming, because they show where the line actually falls rather than where it is drawn.
Exciter from Ottawa in 1983 have a singing drummer, melodic riffs and thrash aggression, and the honest answer is that they precede the distinction. Agent Steel in Los Angeles played thrash with a high clean vocal over the top. Blind Guardian began as a speed metal band and became something else. Early Running Wild and early Grave Digger could be filed either way depending on the album.
These are not failures of the system. A genre boundary is a description of a tendency, and a tendency has a middle.
| Element | Speed metal | Thrash metal |
|---|---|---|
| Vocals | Sung, often high and clean | Shouted, pitch incidental |
| Riffs | Melodic, resolving | Chromatic, percussive |
| Solos | Composed, neoclassical | Atonal, frequently chaotic |
| Drums | Rock patterns at high speed | Hardcore derived, offbeat snare |
| Subjects | Heroism, myth, fantasy | War, addiction, institutions |
| Home ground | Germany, from 1985 | California and the Ruhr, from 1983 |
What happened to speed metal
It turned into power metal and left, which is why the phrase now sounds archaic.
Helloween's Keeper of the Seven Keys albums in 1987 and 1988 took the melodic tendency to its conclusion, added choirs and keyboards and songs about eagles, and the result was a genre with its own audience, its own festivals and almost no overlap with thrash. Within five years nobody was using speed metal to describe anything current.
The word survives mainly as a historical term for the 1983 to 1986 period, when it genuinely was the best available description of a lot of bands, and as a label some modern groups adopt deliberately to signal that they are working in that earlier register.
Why it is worth getting right
Not for the sake of taxonomy, which nobody should care about for its own sake, but because the two words point at different pleasures.
Somebody who likes fast heavy music with big melodies and a singer will find a great deal to enjoy in the German power metal tradition and will bounce straight off Reign in Blood. Somebody who wants hostility and riff architecture will find the choirs unbearable. Both audiences existed in 1986, both were being sold records under the same word, and both were regularly disappointed.
The split, when it came, was useful. It let each tradition develop on its own terms, and it is the reason that forty years later a listener can pick a shelf and know roughly what is on it.
A closely related boundary case, and the one that comes up most often, is dealt with in Is Iron Maiden Thrash Metal?, and the period in which all of these words were still up for grabs is covered in the chapter this belongs to.
What the words meant at the time
Almost nothing consistent, and it is worth being honest about that rather than projecting the modern distinction backwards.
Contemporary press coverage from 1984 and 1985 uses speed metal for bands that nobody would now describe that way, and uses thrash for records that are plainly power metal in retrospect. Record shops filed by whatever the distributor's sleeve said. The bands themselves mostly said metal and left it there.
The distinction described in this article is real and it is retrospective. It was arrived at over about five years by listeners and journalists who needed to separate two audiences that wanted different things, and it hardened only once the two traditions had visibly diverged. Anybody quoting a 1985 review as evidence about genre boundaries is quoting a period when the boundaries did not exist.
Where the two traditions ended up
Both are alive and neither has much to do with the other any more, which is the clearest proof that the split was real.
The melodic tradition became European power metal: symphonic, fast, sung, enormously popular in Germany, Italy, Finland and Japan, with its own festival circuit and an audience that overlaps with progressive rock more than with anything extreme. The hostile tradition stayed thrash, fed death metal, and eventually came back around through the revival.
A listener who walks into a power metal festival expecting Slayer and a listener who walks into a thrash show expecting choirs will both have a bad evening, and forty years ago the record shops were selling both of them the same word.
Sources and notes
Dates refer to original pressings. The characterisation of both genres describes tendencies rather than rules, and the boundary cases named are genuinely contested.
