The term "hard rock" encompasses many styles - Southern rock, heavy metal, alternative rock, grindcore and thrash, just to name a few. But labeling aside, it's all music, right down to the bottom of the big bass drum.

Four new releases from the hard-rock scene display the diverse styles of the genre. Take your pick.- JACKYL crept out of the depths of Atlanta a couple of years back and assaulted the country with its raunchy Southern boogie-blues. The band attacks again with "Push Comes to Shove," which not only sounds like the first album but could be considered sides three and four.

In some respects, that's good. It shows the band is consistent and has developed its own style. But this time the consistency is fair. The album, in its recent weeks on the charts, has become somewhat of a cliche.

The music almost seems a rehash of the earlier grinding blues arrangements with different lyrics. From the opening title cut to the closing "Chinatown," Jackyl whips out familiar images of sex, homelessness and excess.

Even the slow Southern ballad "Secret of the Bottle" could be considered a takeoff of Lynyrd Skynyrd's "Freebird" or Molly Hatchet's "Fall of the Peacemakers." Jackyl also recycles the chainsaw, found on the debut album's "Lumberjack," and chaws out the opening chords to "Headed for Destruction." But all isn't bad.

Lead vocalist Jesse James Dupree has perfected his mix of former AC/DC frontman Bon Scott's growling throat with the likes of Yosemite Sam. Dupree's voice is tight, cynical and rambunctious. And when guitarists Jimmy Stiff and Jeff Worley let their fingers fly, each lead shoves the Southern soul into the listener's face. Hearing "Push" is a fun, twangy trip through deja vu.

- BRUCE DICKINSON, known as the "human air-raid siren" when he fronted the English metal outfit Iron Maiden, has released a followup to his solo debut "Tatooed Millionaire." "Balls To Picasso" is not what "Millionaire" is and definitely not what Iron Maiden used to be. Instead, Dickinson attempts to break free of the myth and focus on the man.

Each song is filled with personal statements on war, peace and oppression. They shy away from the metal feel and lean more toward melodic rock.

Dickinson's voice has lost its edge, but the arrangements and pitches accommodate his newfound lower range. Don't expect to hear throat-cutting screams like the ones in old Maiden hits like "The Trooper" and "Run to the Hills." Instead, he lowers his voice in worthy efforts like "Hell No," "Fire" and the coda to "Sacred Cowboys."

Maiden fans will appreciate the medieval connotations in "Cyclops," the album's seven-minute opener, and the closing "Tears of the Dragon." If Dickinson tried to break away from the Iron Maiden sound, he succeeded.

- THE WHO popularized the rock opera with "Tommy." Other bands, such as Pink Floyd, Styx and Queens-ryche, followed suit through the decades. In 1991, an overblown metal band called Savatage landed itself on the opera-rock list with its 1991 release "Streets."

While Savatage's new album is not a rock opera, it is operatic rock. Yes, there's a difference.

"Handful of Rain" has no flowing storyline, but is filled with nine musical anecdotes and one instrumental. While the whole album "Streets" centered on a young man's demise in an anonymous city's drug-infested alleys, "Handful" provides melodic social commentary on history, current events and a sibling's death.

When guitarist Criss Oliva, the brother of founding member Jon Oliva, died in a head-on collision in 1993, Savatage recruited ex-Testament guitarist Alex Skolnick. Skolnick's musical intuition as a virtuoso guitarist paved the way for "Handful," which is the band's tribute to Criss.

While songs like "Taunting Cobras" and "Symmetry" take shape in a full-power assault of heavy rock and screaming guitars, other tracks like "Chance" and "Stare Into the Sun" paint stories through operatic choruses and classically inspired arrangements.

The title cut uses images of chances slipping through the cracks, and "Watching You Fall" is a rough-and-tumble piece about the war in Bosnia. Zachary Steven's clean, versatile voice hits every flowing, staccato note and lung-bursting sustain. Here, the music, not the cover illustration, becomes the art.

- MENTION BLACK SABBATH and shades of malevolence and gloom come to mind.

Metal's most influential band has finally become the subject of a tribute. "Nativity in Black" brings together some of the loudest and heaviest death-metal, grind-core and thrash-metal bands in the world.

Biohazard, Megadeth, Sepultura, White Zombie and Ugly Kid Joe (OK, maybe UKJ is not as heavy as the others) are just a few of the bands paying homage to the big daddy of gloom.

It's very quaint how each band retains its identifiable style when covering some of "The Sabs' " famous tunes. Megadeth's angry lisp adds new dimension to the neurotic "Paranoid." Biohazard's "After Forever" features death-metal rap, and Sepultura's grindcore rendition of "Symptom of the Universe" growls along.

Not to be left in the dust, White Zombie assails the listener with radio news sound bites of the Charles Manson murders throughout its ultra-violent rendition of "Children of the Grave," and Ugly Kid Joe shoots out a surprisingly tight version of "NIB."

Other bands on the album include Therapy? and the original Sabbath frontman himself, Ozzy Osbourne. While it's unlikely that any band can actually improve on the originals, the covers are demonically delicious.