Who can tell the dancer from the dance?

Stripped to her tights, Ann Reinking has been seen by more people than Bo Derek's braids and Martin Agronsky put together. "All That Jazz" alone was enough to put her reputation firmly in the Cannes, and anyone who ever saw that film thinks he has her number.

But they say in New York that dancers never get top billing. So here she is, veteran of more than half a dozen Broadway shows, two movies, one commercial and an endless string of talk shows -- the woman who turned down roles in "Three's Company" and "Charlie's Angeles." And yet her press kit contains one photo, a scant two inches a copy, and it misspells her name.

Reinking shrugs. Publicity is "a kind of mystique. They completely idealize you, it has nothing to do with reality. The fact that I am a person, that I like to go to bed or eat peanut butter, becomes completely obscured."

Besides, there is more to a career than klieg lights. "I've been getting really good parts, and good money . . . and a lot of offers have been coming in. But you have to keep it in perspective."

Perspective is doubly important when your romantic past, or some bowdlerized version of it, is spread umpteen times life-size in a movie that romps to four Oscars and a Cannes grand prix.

But just because the movie -- written and directed by choreographer/womanizer and overgrown enfant terrible Bob Fosse, about a chor/wo/terrible named Joe Gideon directing his ex-wife in a musical the way Fosse directed ex-wife Gwen Verdon in "Chicago" -- stars former Fosse protege/girlfriend and so on and so on, Reinking doesn't think the movie should be called autobiographical.

"It was just like any other movie. They weren't really people I knew, once you get past the basics," she says, frowning slightly. "It was more Mr. Fosse's wanting to show a side of show business -- one very particular side of show business -- that I happen to know."

And she should know it. Reinking seems exactly the stuff of which gossip columnists' dreams are made: Smalltown girl discovers love of dance, lands penniless (almost) at the edge of the Great White Way, works her way up to featured parts, finally is spotted by big director and -- "It's showtime, folks!"

But no show, Dancers are generally extroverts because dance requires the simultaneous devotion of the body and the spirit. The body is a temple -- and to the least reserved of muses. In real life, far from being "The Tonight Show" starlet, Reinking is surprisingly undemonstrative.

And, in real life, she and Fosse came to a romantic, though not professional, parting of the ways. "The people who help you, teach you, whatever -- it's for you, not them. They don't want to be a crutch forever."

Reinking starred in Fosse's 1978 hoofer-revue, "Dancin'," although she spent every spare moment working on an after-curtain nightclub act. When Fosse offered her the role of Gideon's dancing girlfriend in "Jazz," she said fine. But no autobiogaphy.

"I created [the girlfriend role] the same way I've created any part I've played. Anyway," she says, executing a neat sidestep, "I don't mind talking about 'Jazz, but I've been talking about it for a year now."

Reinking, 29, is a kind of physical puzzle, large features somehow fitted into a small package. Although her mouth is small, her eyes are huge, cornflower blue and Technicolor white, and her cheekbones, like the hipbones that Astaire'd down the staircase in "All That Jazz," wing out from the rest of her.

She comes from a large family that uprooted year after year when she was a child, finally settling in Seattle. She discovered dance relatively late, when she was 11. Six years later when she graduated from high school, she carried her life savings (a little less than $500) to New York to find the big break.

Just about the time she realized how little $500 was in New York in the late '60s, she joined a road company of "Fiddler on the Roof." After those six months, Reinking says, "I'll never go on the road again."

A couple of acts later, punctuated by blackouts of temporary unemployment, we find Reinking in a small speaking part opposite Katharine Hepburn in "Coco."

"She told me I could act, and I thought that was great!" Reinking's throaty giggle is the most backstage-chorine thing about her. "Of course, I believed her."

Reinking first worked for Fosse in the chorus of "Pippin." In 1976, after starring as Joan of Arc in "Good Time Charley" and replacing Donna McKechnie in "A Chorus Line," Reinking replaced, under Fosse's direction, Verdon in "Chicago." It remains her favorite role, despite the peculiar triangularity of the casting.

"A year earlier I had been doing Joan of Arc, and then here I am, she's a sweet girl but she's kind of a tramp, in a blond wig -- it was like going from saint to sinner." That froggy giggle again. Blond wig intact, she took a starlet role in "Movie, Movie" and the lights went on in Hollywood.

Reinking is guest-starring tonight at Wolf Trap with the American Dance Machine, a human repository of great American choreography. Founded in 1975, the Dance Machine has reconstructed more than 40 dances from Broadway musicals of the past four decades: works by Agnes De Mille, Gower Champion, Ron Field, Michael Kidd. Tonight's program for instance, will include numbers from "Gentlemen Perfer Blondes," George M," "Paint Your Wagon," "Carousel," "Bye Bye Birdie," "Cabaret," Can-Can," "The Boyfriend, "Brigadoon" and Grease." Reinking will appear in eight selections.

Dancing is a profession of the young, and like Shirley MacLaine and Chita Rivera, Reinking expects to find her ultimate security in an acting career. "Let's fact it," she shrugs. "The ones who are still on top past 40 are the exceptions."

There are plenty of scripts rolling in, "mostly girlfriend roles," but many of them call for nudity or obscenity, and Reinking doesn't seem to think she could pull that off. She's just finished a commercial for New York's WNEW, a top-hat-and-tails production, and after tonight's performance, she starts work on a CBS dance special starring Julie Andrews and Rudolf Nureyev. In the offing is another Broadway show.

"Things keep coming up," she says, a la Mama Rose. "That's the great thing about the American system: You can make it big, and you can get rich." t

So long as they spell your name right.