AS SCREENING ROOMS GO, an economy-class seat on a transatlantic flight is not the choice of most film critics. But when I noticed my seatback TV monitor was playing “The Departed,” I realized I had a wonderful opportunity: In the bag at my feet were my laptop and a DVD of “Infernal Affairs,” the 2002 Hong Kong film on which Martin Scorsese based his Oscar-winning cop epic. Over the next four hours or so, I watched them both, first the remake, then the, uh, make.

Both movies trace the same basic plot: In each, a cop (Tony Leung in “Infernal Affairs,” Leonardo DiCaprio in “The Departed”) infiltrates a major criminal organization, while a bad guy (Andy Lau and Matt Damon) rises to the highest levels of the police unit that happens to be investigating the gangsters. Pretty soon, each side realizes it has a mole, and—whaddaya know?—the spies are assigned to root each other out.

As the stars engage in this game of cat and mouse and cat, they struggle with the psychological trauma of having to live with a double identity. Well, sort of. While DiCaprio emotes furiously through his facial hair and Leung makes his look mustache sad and wispy, Damon and Yau simply carry on with their cushy lives (both have hot girlfriends and awesome apartments), getting antsy only when it appears that their facades may be about to crumble. And, of course, those facades do eventually crumble, resulting in gun battles, bodies being thrown from rooftops and some very tense text-messaging.

But given these plot particulars, does either film do a better job? Should you spend 101 minutes with Lau and Leung, or 151 with DiCaprio and Damon? And can any movie “based upon” another ever achieve the frisson created by the original?

In a word: yes. Skip “Infernal Affairs”; watch “The Departed” instead.

I realize this may come as a shock to the fanboys and purists out there, but Hong Kong cinema can be just trashy and superficial, too. Sappy music, montages substituting for storytelling, sketchy backstories and obscure motivations—these are the province not only of American hacks.

And “Infernal Affairs” takes advantage of every cheap technique pioneered in Hollywood. While “The Departed” is careful to establish the histories of its mirror-image leads—DiCaprio grew up between two Boston homes, one working class, the other genteel; Damon was raised by his grandmother in a tough neighborhood—”Infernal Affairs” merely alludes some hazy past, trying to outline Yau’s and Leung’s histories with a pair of scenes in which each acquires the assignment that will dictate his destiny.

Where did these guys come from? And what is there to show us they’re grappling with the choices they’ve made? Leung, my favorite Hong Kong actor (he’s the George Clooney of Asia), knows how to appear weighed down by the past—but in this case it’s indistinct, all reaction and no action. DiCaprio, meanwhile, starts barroom brawls, threatens low-level drug dealers with handguns and takes risks that could expose his charade to the gangsters who surround him; when he complains of nightmares and sleeplessness to a therapist (who happens to be Damon’s girlfriend), we believe him.

Yau, too, plays an archetype rather than a character. What does he hope to gain from his deception, other than a comfortable existence and high-end stereo equipment? The movie doesn’t bother to tell us; Yau is like every other cop in the movie, competent and bland, even though he’s working for the bad guys. Damon, however, is a creature of ambition: He buys an apartment with a view of Boston’s capital building, and nakedly climbs the rungs in the department, earning the enmity of many of his colleagues. All the while, he looks deeply uncomfortable with the life he’s built for himself, and even struggles with impotence.

“Infernal Affairs” requires the viewer to supply all this. We’re supposed to take the basic structure—Cop (as gangster) vs. Gangster (as cop)—and imagine how it would feel to be each one.

This extends even to the minor characters. Three different women circle Yau and Leung, with virtually no explanation of who they are (Yau has a hot girlfriend who’s a novelist, Leung sees a hot therapist and once runs into his hot ex on the street). “The Departed” wisely condenses these into one woman. The police captain (Anthony Wong Chau-Sang) overseeing Leung is stoic but one-note, while DiCaprio’s captain (Martin Sheen) gets not only a religious fixation but a foul-mouthed sergeant (Mark Wahlberg) who turns out to be the only one Leo can trust.

Finally, the head gangster in “Infernal Affairs” may be colorful and bad-tempered, but Eric Tsang is no Jack Nicholson, whose unstoppable insanity is fully realized and given an extra twist. (He’s an FBI informant!)

Let’s not even get into “Infernal Affairs“‘s awkward ending, which plays as if the producers suddenly ran out of money, or its cheeseball music or swirling cameras or hastily sketched Buddhist/Taoist themes. It’s a clever movie, but poorly thought through, and you’re better off dropping $10.75 for two and a half hours with Scorsese’s latest opus.

But does Marty deserve an Oscar? Apparently, yes.

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Matt Gross writes the “Frugal Traveler” column for the New York Times, and is TripmasterMonkey’s editor-at-large.