Away from work, Vanessa and she "are both political women," Jane Fonda is saying. "And in 'Julia,' the fact that we both play women who were brave and committed gives the film an extra dimension. There's an overlapping of life and fiction, fiction and life . . ."

"Nonsense," snaps Vanessa Redgrave, a steely, six foot presence of coiffed Raggedy Ann curls.

Her large blue eyes turn icy if you mention Fonda's theory of a clear link between their acting and radical politics, or if you poke into subjects she would rather avoid. These include her personal life, her attitude toward friendship with women and, especially, whether her preaching at ban-the-bomb rallies and her political experience (a losing race for Parliament on the Trotskyite ticket) helped her with the character of Julia, the rich American anti-Nazi activist whose friendship Lillian Hellman (played by Fonda) sketched in "Pentimento," the memoirs on which the film is based.

No, says Redgrave politics had no bearing on the part. Yet she admits to a retrospective displeasure with Antonioni's "Blow-Up," in which she played a bourgeois fashion model, and she says, "I've known some very excellent artists who have prostituted themselves for what is reactionary . . ."

She also smarts at the story Liv Ulmann tells in her books "Changes," of Redgrave's stopping by the Swedish actress' hotel to hard-sell her into writing a check to a political organization back home. Later, Ullmann says, fearing that the money might be used to buy guns for someone like the IRA, she nesty International.

Much easier to talk to Fonda, who at least admits to mixing life on and off the screen. Her bankrolling of politician-husband Tom Hayden's short-lived Senate campaign has been thoroughly reported, as have her plans to pump future and to help other California candidates who will fight for what she calls "economic democracy."

On the set of "Julia," Fonda and Redgrave say, they agreed to disagree, never talked politics and got along just fine.

But if their politics differ, they are strikingly similar in several other ways: Both have sneaked up on 40; they have inherited some powerful acting genes from their fathers (Henry and Sir Michael); they are both gifted performers.

Redgrave, whose stage roles have brought consistent acclaim, was nominated as best actress in 1970 for her portrayal of revolutionary ballet teacher Isadora Duncan.

Fonda, chosen as best actress for her role as a callgirl in "Klute," has long since traded in the bleached-blonde allure of "Barbarella" for earthy Barricade Chic. Long, frizzy brown hair, no makeup save for a wisp of rouge to enliben a long, pale face, and clogs. Tiny lines are etched about her mouth and crows' feet stamped gracefully about the eyes - none of which, she says, bothers her now.

"Not only am I not in a panic about my wrinkles and my age," she says, "but not a day goes by that I don't realize you get wiser as you get older. You stop blaming others for patterns you realize are your fault, and you begin to realize 'I shouldn't do that because it will lead to this." Ten years ago, I would have been in one helluva panic about becoming 40 years old, 'cause that's all there was for me. But my life has substance now."

Fonda, curled up on the gold silk coach in her attorney's antique-laden Broadway apartment, orchestrates the words with long, bony fingers. She has just flown in off the campus circuit, where she has found it, sadly, hard to rekindle the student fervor of the good old anti-war days.

She courts a modest image now - $40,000 home, devoted wife and mother, old cars for transport, no servants and so on - along with "positive" acting roles Hollywood has recently unveiled for its women. Roles like Hellman in "Julia," parts Fonda hopes the public will pay for so she can play in other films that might inspire people to "work together to achieve seemingly insurmountable tasks," and do for others what Julia did for hellman.

"I've never had a friend like Julia," says Fonda, "someone who was always ahead, pulling me to extend myself as a human being. But if I were to fantasize such a friend, she would like Vanessa Redgrave. I don't agree with her politics, but she has that kind of courage."

Courage, adds Fonda, like that of the J.P. Stevens textile mill organizers, or the North Vietnamese women she met who, like Julia, made a commitment to have children out of a belief that the "future would be better."

"This country is filled with people like Julia," she says, people who fight to help others get by on more than a pittance, "people who died to win an eight-hour day."

"Shameful," Fonda calls the gobs of money she earns from roles to hers in "Julia." For a time in the 70s, her torment over her enourmous income was so great that she considered giving up acting altogether.

"The question is simply, "When wealthy or famous people because part of a movement that speaks primarily to the interest of the poor and the middle class, what do you do with the unecessary profit? Once I resolved that confict, I saw no reason to give up acting."