Both France and the United States have opened in their capitals new national art museums. Pontus Hulten, the director of the celebrated and controversial Beaubourg Museum in Paris, came to Washington recently and looked at the East Building of the National Gallery of Art.

"It is too elegant," he said.

Official visitors from France do not typically complain of our excessive elegance, but Hulten is not typical. He is known in his profession as a chance-taking iconoclast. He wore a dark blue suit (the museum director's uniform) but his was rumpled corduroy. He likes to ride a motorcycle rather than a limousine. And though he directs Paris' National Museum of Modern Art, he is not a Frenchman, but a Swede.

The two museums do have much in common - striking modern architecture, strikabstract pictures and enormous crowds. The art-and-culture center in the Plateau Beaubourg has attracted more than 10 million visitors since its opening in January 1977; and the new East Building is a comparable draw.

"But there are differences," said Hulten. "Your museum seems a temple. Ours has the spirit of a factory instead."

It is a factory with a dazzle. Its materials are industrial - steel tie-rods, panes of glass, its structure is exposed, not encased in marble, and glass tubes containing escalators snake up its facade. It is painted in bright colors, and glows at night. Many claim to loathe it. Some say that it resembles a huge and crowded spaceship that unaccountably has touched down a few blocks from Notre Dame.

"Its glass walls are transparent. I like that," Hulten said. "It is time that we took pictures out of their old golden frames and out into the streets."

TThe complex known as Beaubourg is not only a museum: It includes a public library - the first in France - and centers for the study of industrial design, the history of film, music and acoustics. The acrobats and strongmen, fire-eaters and guitarists, who perform all summer long on the plaza at its door, have brought to the Beaubourg the high spirits of a circus.

There is nothing frivolous about the marble-walled East Building. Imposing as a pyramid, it is a treasure house for art.

When Hulten starts to list the pictures he's acquired - "The Deep" by Jackson Pollock, "Shining Forth" by Barnett Newman - he does not talk of masterworks. Instead he likes to speak of "this bomb that is art."

When Hulten was director of the modern museum in Stockholm, he acquired a high-speed racing car, a Lotus Formula One, as a piece of modern sculpture. Another art machine shown there, this one by Jean Tinguely, accepted coins from visitors and spewed out abstract drawings.

"New art of this sort has been, I feel, desacralized. It need not be exhibited in an atmosphere of mystery. It has stepped out of the frame and down from the pedestal, into real life.

"In Sweden," he continued, "we thought of our museum as a kind of home for homeless new expressions, for movies that couldn't be shown in the movie houses, for music that couldn't be heard in the concert halls. In the 1960s everything seemed possible. It was a springtime situation. Everything seemed new as if seen for the first time, and by a new public, too."

The Beaubourg opened with a retrospective exhibition given to a Frenchman, the late Marcel Duchamp. Shows called "Paris-New York" and "Paris-Berlin" have been seen there since; so have recent paintings by Warhol, Jasper Johns, Sam Francis and Claes Oldenburg - men whose works would not seem out of place in the new East Building.

"It is not the art that's different; it is the setting," Hulten said. "We do nothing revolutionary. We are not attempting to overthrow the cart. It is a question of atmosphere, of making things accessible, not frightening, not pompous. We wish to present works of art as one might see them in a studio. Paintings, music, film, industrial design all work together at Beaubourg. The East Building shows art only. Our proposition is more romantic, maybe even more old-fashioned, than is yours. You cannot say that one approach is better than another. But the two are different, there is no doubt of that."