TWO CONCURRENT exhibitions, one a collection of photographs of women, the other a collection of photographs by women, speak volumes -- but most loudly about two women in particular.

"Annie Leibovitz: Women," debuting at the Corcoran Gallery of Art on the occasion of the publication of a slick picture book of the same name, says as much about the celebrity portraitist as it says about her subjects: not just hot shots with such instantly recognizable names as Venus, Serena and Gwyneth, but what's-her-faces like champion mountain biker Missy Giove and camouflage-faced Army grunt Cherish Mitchell.

Over at the National Museum of Women in the Arts, where the traveling exhibition "Defining Eye: Women Photographers of the 20th Century" has taken roost, we learn more about Helen Kornblum, the St. Louis psychotherapist from whose collection the pictures come, than we do about the artists who took them, artists such as Cindy Sherman, Dorothea Lange, Carrie Mae Weems and Mary Ellen Mark.

What is a survey of 81 photographs by 80 photographers supposed to tell us about photography, about women or about the 20th century? And what is a show of 74 portraits of women and girls by a magazine photographer trying to say about the female today, except that she can be surgeon, general, astronaut, actress, supermodel, battered wife?

According to critic Lucy Lippard, a group show like "Defining Eye" does something else entirely. "An art collection," writes Lippard in the catalogue, "perhaps especially a photography collection, documents the ongoing construction of the collector's self-portrait."

So too, as Susan Sontag suggests in her introductory essay to the Leibovitz catalogue, if a photograph is an opinion, it is clear to whom these monumental opinions at the Corcoran belong. When it comes right down to it, says Leibovitz, in town recently to open her show, "These are ultimately pictures of women I like and admire."

Admire. That's a word that comes up again and again while listening to Leibovitz. She especially admires comedians ("manic-depressive individuals who channel their misery and intelligence into making people laugh"), but there are none on the walls of the Corcoran -- despite the fact that Ellen DeGeneres and Rosie O'Donnell are in the book. She admires tennis stars Venus and Serena Williams for their strength and power and their "[expletive] you" attitude. Wiry minor-league baseball pitcher Ila Borders is "glamorous," but so are the grimy Alabama coal miners Leibovitz shot, one of whom put four daughters through college.

"I was crying when she told me that," says the photographer.

What better criteria did she need in selecting which images she would publish out of the many she shot -- in color and black-and-white, lit and unlit, straightforward and set-up -- for this highly personal statement of woman's infinite variety? "If it makes you cry," she says, "it goes in the book."

And so there's the moving tribute to her mother, who was afraid she would look old, but who mainly just looks querulous. "Pictures of people I know are the hardest to take," says Leibovitz, who is torn between wanting to make them look good and make them look real.

Speaking of which, two of the show's most striking pictures are of Las Vegas showgirl Susan McNamara, who is shown in her street cloths and eyeglasses next to a shot of her in full drag. According to Leibovitz, the irony lies in the fact that, "she is a woman who dresses up to look like a woman." But next to this topless insect-queen with spangled antennae and a G-string, McNamara's Plain-Jane self only begs the question: Which of these two women is more "real"?

Sex entrepreneur Heidi Fleiss made it into the book because she represents a certain type (hey, variety is the watchword here). She didn't make it into the Corcoran, however, perhaps because she wasn't admirable enough.

One omission Leibovitz does regret is Sigourney Weaver. The portrait of the actress's fishnetted bod is "important," says the artist, because, "here's a woman at 50, not afraid to pose as someone sexy and alive." At the irony of this comment, Leibovitz, also 50, rolls her eyes.

When collector Helen Kornblum speaks about her photographs, she calls herself a "proud mom." Although she doesn't make them, she's been buying them for 20 years, gradually evolving from a gender-blind ecumenicism to an exclusive focus on the acquisition of work by women photographers. Drawn from Kornblum's private, political and rather idiosyncratic, collection, the photos of "Defining Eye" primarily explore issues of feminine identity and experience (the title plays on the eye/I pun), with images of men sparse but not absent.

How many photographs she has Kornblum can't say, or won't. "Collecting is not about numbers," she insists, "but purpose and content."

That's good, because one shouldn't approach "Defining Eye" as a comprehensive overview of anything -- least of all of "Women Photographers of the 20th Century," the show's sweeping subtitle notwithstanding. It could be called "Women Photographers From the Collection of Helen Kornblum," except that this self-described "private person" would disapprove of such grandiosity.

Unlike Leibovitz's work, there are few nudes in the Women's Museum show ("The Russian Dancer Nikolska at the Parthenon" by Nelly (Elli Seraidari) and Anne W. Brigman's "The Heart of the Storm" come to mind). "I have not, do not, and will not collect that work," says Kornblum. No prude she, Kornblum explains that her gentle agenda has no room for sexual objectification. Yet the show features Hannah Wilke's "S.O.S. -- Starification Object Series," a self portrait of the striking artist with tiny vulvas made of chewing-gum stuck to her face.

Although children and motherhood are recurrent themes in Kornblum's collection, you won't find anything along the lines of Sally Mann's controversial photographs of her kids. Kornblum finds Mann's sexually-charged images "beautiful but exploitative" and does not believe that young children are capable of informed consent.

What you will find are several images about food and eating (e.g., Sandy Skoglund's shot of beach-blanket Barbies on a bed of French fries, Laurie Simmons's color-saturated chorus line of red petits-fours perched on the plastic gams of miniature dolls). In Kornblum's practice, she does not specialize in eating disorders, but such topics nevertheless come with the territory.

There's lots of collage and multiple exposure (Claude Cahun and Holly Roberts, among others). What that's about, says Kornblum, is the "multilayered" way in which women view the world -- not that men don't, but that Kornblum feels women didn't used to be allowed to look at life -- or themselves -- that way.

Much of the work is, as Kornblum seems to be, balanced, thoughtful and introspective, neither strident nor Pollyannaish but somewhere in between -- work like Ruth Orkin's "American Girl in Italy," which reflects a feminist aesthetic in the powerful way it lays bare the unique experience of being a woman.

In Orkin's famous 1951 photo, a young female tourist walks a gantlet of leering men who, as the wall text states, "gather around the woman like a pack of wolves." Because of its capacity to evoke a spark of recognition in the viewer, the picture is a touchstone for women of every generation who have ever experienced the street ogle (perhaps even for the more enlightened members of my own gender who feel its accusing finger lay a guilt trip by association on them).

Implicit in both of these shows is the question whether, because of our separate life experiences, women look at themselves in the same way that men do. Or is there, as Kornblum and Leibovitz seem to suggest, a need for women to show themselves -- and us -- what it is like to be female?

"Not to sound trite," says Kornblum, referring to photography's tradition of sexual segregation between the (male) artist and the (female) model, "but what it comes down to is this: At long last, women have finally put themselves into the picture."

ANNIE LEIBOVITZ: WOMEN -- Through Feb. 28, at the Corcoran Gallery of Art, 500 17th St. NW (Metro: Farragut West). 202/639-1700. Web site: www.corcoran.org. Open 10 to 5 daily except Tuesdays; Thursdays to 9. Admission to the exhibition is $5; $3 for students and seniors. Tickets are available at the museum or through TicketMaster at 202/432-7328. Admission to the museum is by suggested donation of $3; $1 for students and seniors; $5 for family groups.

DEFINING EYE: Women

Photographers of the 20th Century -- Through Jan. 9, at the National Museum of Women in the Arts, 1250 New York Ave. NW (Metro: Metro Center). 202/783-5000. Web site: www.nmwa.org. Open 10 to 5 Mondays through Saturdays; Sundays noon to 5. Admission is by suggested donation of $3; $2 for students and seniors.

Public programs associated with the exhibitions include:

Wednesday at 7 -- "Filming the Twentieth Century: Visions From Women Directors." The National Museum of Women in the Arts screens "Go! Go! Go!," a short black-and-white film by Marie Mencken from 1962-64, and "The Cool World," a black-and-white feature from 1963 by Shirley Clarke. Admission $5; $3 for students and seniors.