It would be hard to guess, simply from seeing their works hung in the same room, that the painters Andrew Hudson and Blaine Larson are fast friends. Nonetheless, this friendship is the reason for their show that opens today at the Corcoran Gallery of Art, the "special phenomenon" that prompted curator Clair List to bring their works together.

Blatant differences between the works of the two artists seem more important than similarities. Hudson is a figurative painter and Larson an abstractionist. Larson's robust attack plays against Hudson's underlying elegance, his thick surfaces contrast with Hudson's overall flatness, his clear joy in the messiness of paint runs counter to Hudson's basic tactfulness.

In a catalogue interview with the two artists, List asks the quesion, "Are you ever worried . . . that you perhaps will start borrowing from each other's work?" Hudson replies, "No, because we're not alike; we don't clash. We are totally different from each other."

The story that Hudson and Larson have to tell is unusual. Their cooperation is not the brief, intense kind of cooperation between like-minded artists that produces very like-minded art: Pablo Picasso and Georges Braque at the beginning of Cubism, for instance, or Theo van Doesburg and Piet Mondrian at the beginning of "De Stijl," or, closer to home, Morris Louis and Kenneth Noland in Washington in the mid-'50s.

And yet their friendship, dating back a decade or more, has evolved into a regular exchange of studio visits during which one artist subjects the other's recent works to "objective analysis," in Hudson's words.

Often this has led to dramatic changes in the work. Hudson recalls how Larson and another artist (Jennie Lea Knight) got him started on figuration by calling attention to a little portrait that he "had left out to throw away in the morning." On the other side he tells of a visit to Larson's studio last summer to look at Larson's new series of paired diamond-shaped paintings. "There were several cases," Hudson says, "where I could see better than he could -- which canvases should go with which or which ones didn't work at all."

In the Corcoran exhibition this is all pretty much hidden: there is no attempt at all to trace specific cause and effect. Larson's work is better -- that is, by and large it more fully accomplishes what he sets out to do, and this is to set up unpredictably resonant exchanges between colors and forms upon coupled diamond-shaped canvases. The challenge of the format is its very precariousness; the painter must contradict the viewer's ever-present impulse to read the halves of the painting separately.

On occasion Larson unsuccessfully attempts to resolve this tension simply by contrasting totally unlike paintings -- a plain, unpainted diamond touching one that is full of incident, for instance. (Was this course recommended by Hudson? We'll never know.) More often, he ties things together precariously and resourcefully by pulling out all the stops, using everything he has learned in 15 years as a serious painter with genuinely invigorating results.

The exhibition catches Hudson in the midst of a transition from working on paper to working larger and on canvas, and while there is much good to be said about his work, the transition is not successful as a whole. For a decade or so Hudson has been drawing the same three or four models in informal poses. His familiarity with the models helped him to create a satisfying, rough sketching style and a world with its own interesting, laid-back psychology.

In the larger canvases this world is not nearly so cohesive, perhaps because the bigger size emphasizes Hudson's attempts to fuse figuration and a very formal type of abstract art. He has successfully enlarged his sophisticated stick-figure drawing style, but most of the other things he tries -- spurred on by Larson, perhaps? -- including collage, cutouts, patches of hand-prints or lavish soakings of wet paint, call attention mainly to themselves.

So, the exhibition is an interesting progress report on the works of two artists in mid-career. Although interesting, the story of their friendship in a sense gets in the way of looking at the exhibition, on view through Feb. 7.