The Oscar winner says she's opted to represent herself as a woman by not stripping down for her roles, and being physically vulnerable -- although, she's quick to say she's not shading other women who decide to do it.

Julia told Vogue UK it's just basically a deliberate decision ... as she put it, "choosing not to do something as opposed to doing something."

What makes that path interesting is that she has starred in some sexually explicit movies, such as Mike Nichols' "Closer" ... and, of course, her most famous/beloved role is as a prostitute! Albeit, a prostitute in a Disney movie.

Speaking of the biz in Hollywood ... she tells the publication it's totally changed since she started out -- everything seems too cluttered now, and being famous looks exhausting, she says.