Character: Spud, the beloved spaz
Fate in book and movie: Goofy speed fanatic who hates working.
Fate in play: Nonexistence. Poor Spud gets morphed into Mark, who gets his monologues, and Tommy, who gets aspects of his personality.
Character: Mark Renton, our hero
Fate in book and movie: Disses his druggie past and finds wildly happy ending.
Fate in play: Without giving away the wind-up, a not-so-happy ending.
Character: Begbie, drunken psychopath
In the movie: A walking, talking commercial for testosterone and two-dimensional violence who loves to make people bleed.
In the play: A still-violent and misogynistic asshole, but with a soft spot.
Character: Diane, the underage club kid
In the movie: Dishonest. Tells Mark she's underage after he has sex with her.
In the play: Obsolete. Replaced by two other girls, neither of whom tricks anyone into a horizontal bop.
Drugs of Choice
In the movie: Heroin, period.
In the book and the play: Ecstasy. Heroin. Everything in between.
The Final Word
The movie: "Being a junkie is fun!"
The book: Nails the misery of the druggie scene.
The play: Somewhere in between.