In case you're having a hard time telling the difference between "Deep Impact" and "Armageddon," here's a handy guide: The former is the "killer-rock-from-space" movie where too little happens, while the latter is the one in which way too much happens.

And while that may sound like a rather simplistic way of distinguishing which movie is which, it's pretty valid.Where "Deep Impact" attempted to be a somewhat thoughtful science-fiction thriller, "Armageddon" sets out to be a much more exciting one.

Ironically, neither really succeeds.

"Deep Impact" moved so slowly and tried to develop so many characters that it quickly turned into a snoozefest. "Armageddon" is far from boring, but it's chock-full of explosions and loud noises, which becomes annoying in a hurry.

That's not a complete surprise, considering who's behind the film - director Michael Bay and producer Jerry Bruckheimer. Their previous collaborations, 1995's "Bad Boys" and 1996's "The Rock," subscribed to the pace-it-fast-and-make-it-louder philosophy.

Unfortunately, once you take out all the spectacular special effect sequences, all that's left are some half-hearted attempts at characterization - mostly through one-liner dialogue.

One correct storytelling decision the filmmakers made was jumping right into the action. "Armageddon" begins with scenes of the Earth being pelted by dozens of "tiny" meteors. These basketball-size rocks inflict heavy damage on Manhattan, destroying some of the New York borough's most recognizable landmarks.

However, all the devastation is just the warmup for the arrival of a much bigger asteroid. This Texas-size body is on a direct collision course with Earth.

With just 16 days to either destroy the asteroid (highly unlikely) or at least divert its path, NASA Executive Director Dan Truman (Billy Bob Thornton) recruits some unlikely heroes, a crew of rag-tag oil drillers led by Harry Stamper (Bruce Willis).

The scheme is to send the wildcatters into space, where they can land on the asteroid, drill into its surface and implant a thermonuclear device, which should be able to split the gigantic metallic object and send it off course.

Obviously, things don't go as planned, starting with a disastrous docking/refueling maneuver and a very rough landing.

In addition to all the outer space and earthbound mayhem, there's also a soap opera romance involving Harry's daughter Grace (Liv Tyler) and his best driller, A.J. Frost (Ben Affleck). But it's treated as superficially as every other dramatic development.

As mentioned, the script (written by committee, including frequent Bruck-heimer collaborator Jonathan Hensleigh) tries to develop characters by having them spout one-liners. That might work for a comedy, but this is supposed to be straight science-fiction.

And frankly, the characters just aren't that interesting. Willis practically mails in his performance, while Thornton looks uncomfortable playing a "normal" person for a change.

Of course, Bay's quick-cut direction doesn't help, as it makes the film look more like an extremely drawn-out music video.

"Armageddon" is rated PG-13 for violent science-fiction action, fist-fighting and gunplay, profanity, vulgar references and some lewd dancing and partial female nudity in a stripclub scene, along with brief gory makeup effects.