The Hamptons are Gucci and Pucci, and Martha's Vineyard is flip-flops. The Hamptons are sit-down dinners. Martha's vineyard is spaghetti and clams and lobster in the back yard.

There lies the difference between two vacation spots favored by some of the most affluent, well-to-do and wellknown Washingtonians and Easterners.

Or, as one knowledgeable woman puts it, "In Martha's Vineyard you see a lady in a straw hat padding through her garden picking vegetables. When you drive through Southampton you see the butler in a blue-and white striped uniform crossing the vegetable patch carrying the fresh vegetables."

Both Martha's Vineyard, off the coast of Massachusetts, and the string of towns on Long Island called the Hamptons are bathed by the waves of the Atlantic. Each area boasts green fields and high real-estate prices.

But the Hamptons -- at their ritziest are the Maidstone Club (tennis) in Easthampton and the Beach Club (swimming) in Southampton and the Meadow Club (tennis) and the Shinnecock Club (glof). Martha's Vineyard has the Vineyard Haven Yacht Club " a bungalow with a bunch of kids hanging out the windows and short-order cooks," said one Washingtonian.

Both have their share of celebrities -- Robert De Niro has been known to cruise through a Hamptons hardware store. Writers Joseph Heller, Irwin Shaw and George Plimpton all have houses there.

On the Vineyard you might see Beverly Sills, Walter Cronkite, Lillian Hellman, Carly Simon and James Taylor.

Residents of both places cherish their green fields (manicured or otherwise) and perish at the thought that another person might move in and crowd another field.

As a result, both areas have developed fiercely loyal coteries of vacationers and summertime residents who occasionally sling shots at each other's vacation spots.

The Hamptons are for people addicted to cocktail parties, formal dress and a there-to-be-seen syndrome, Martha's Vineyard fans smugly claim.

"I've never heard anyone talk shop here," said Washington resident Jayne Ikard, who summers in Edgartown and Chilmark on Martha's Vineyard. "I've never heard Walter Cronkite give his viewpoint on any political or national issue.

"The people who stay in the Hamptons have to all be together to be sure they'er as important as they read they are," Ikard continued. "They wouldn't be happy walking the beach alone or picking a blueberry. I really think the people who come to the Vineyard are more secure-less neurotic. In the Hamptons they need their egos massaged."

Ego massaging, Hamptons residents sniff. That's exactly what goes on in the Vineyard, some Hamptons residents will tell you.

"People in Martha's Vineyard spend a lot of time praising themselves for (a lot of time praising themselves for their moral purity," said writer Nora Ephron, who summers in Bridgehampton, "and they claim this while rushing from lunch to dinner and cocktails. They seem to be compelled to say they'er hiding in their basements writing novels."

But Hamptons residents rightly claim there are distinct differences between the Hamptons town in people and their style of living. In fact, there is so much difference between them that residents of Southamption rarely venture into Easthamption some 20 minutes away, according to Southampton resident Darcy Damgard. "You just get settled in your ways," she said.

Starting west and moving east, there is Southampton, which is old and moneyed and more formal-party oriented. Next is Watermill, which is less moneyed. Then come Bridgehampton and Wainscott, both of which have become retreats for the intellectual/artistic/literary communities. Easthampton is more a mix of established society plus business people and more literati. Amagansett comes next with a variety of artistic and literary types. Finally, on the tip of Long Island, is secluded Montauk, favored by actors and actresses, who have included Barbra Streisand, Diana Ross and Al Pacino.

The writers and artists who settle into the Hamptons eschew the traditional Hampton formality.

"The formal people are in Southampton," said writer Joseph Heller. "They wear madras and red-and-green-pants. We never see them."

"Southampton is a very different world," said artist Polly Kraft, who, with husband, columist Joseph Kraft, goes to Wainscott for the summers. "We wear jeans all day. That's the way we go out to dinner."

But many among the informal of the Bridgehampton/Easthampton/Wainscott set end up partying with each other, in much the manner -if not dress -- sniffed at by Martha's Vineyard residents.

"I was once invited to someone's house in the Hamptons for a few days," said one writer," and they told me, 'There is nothing going on, it's really quiet, bring lots of books.' So I did And when I got there, it turned out to be wall-to-wall parties."

So, it comes down to whom you want to spend your summer vacation with (even if it includes work).

"Where would you rather be?" said Barbara Howar, who stays in the Hamptons. "Rehoboth Beach or someplace where you might have dinner with Joseph Heller?"

Or, more generally, where would you rather be -- with the people from New York or the people from Washington?

"The trouble with the Hamptons is you see the people you see all winter long in New York," said humorist Art Buchwald. "In the Vineyard people haven't heard the jokes you've been telling all winter long. In the Vineyard you see new people -- Professors and psychiatrists."

"We wanted to get away from the Washington crowd that goes to the Vineyard," said one Washington professional, who chose the Hamptons.

Martha's Vineyard residents paint a pastoral picture of sun-soaked nature lovers who've left their suits and their silks at home -- to seek the quiet country.

"We read a lot", said Buchwald about residents of Vineyard Haven, a dry town which closes down effectively at 9 p.m. "Or we meet in each other's houses to find ways to lick zoning. You have to understand that everybody who comes to Martha's Vineyard wants to be the last person to come."

Yet, some say Martha's Vineyard will soon succumb to the trendiness that Hampton residents are accused of.

"I hear they've got permission to open a disco," Heller said, referring to the new Vineyard night spot, Hot Tin Roof. "The place is going downhill. Everybody with true class will be in the Hamptons next summer."

There is also another very distinct geographic trait which separates the two places and fuels a certain rivalry. The Vineyard is an island. The Vineyard is an island.

"I don't like to live on islands," said Irwin Shaw, who spends time in the Hamptons. "It's too hard to get off them."

"You can be fogged in on Martha's Vineyard and you'er stuck," said a Southampton resident about Martha's Vineyard. "This plane won't fly for days. Well, there is the ferry. But it's like taking the subway. When I go from Washington to Southampton, I fly to Islip. Then I get picked up by my caretaker in my car."

Now, in all fairness there are parts of Martha's Vineyard that can match Southampton Formality blue blazer for blue blazer -- Edgartown, for example. "In Edgartown," said Buchwald "they'er all blond and come from Connecticut. They wear yachting caps and the insignia of their yachting caps on their blazer pockets. And they all intermarry."

But Hampton residents admit that the specter of formality exists in someplaces -- mainly Southampton.

"Four years ago", said a Washington Woman who summers in Southampton, "four nights out of five, we wore black tie. Things are changing. Last summer we only went to one formal."

But even as both places get more informal and more trendy, the exchange of barbs will probably continue.

"When the weather's bad," said Buchwald, "we say at least we'er not in the Hamptons.' It's no fun when you're on vacation, unless you can look down on some place else." CAPTION: Illustration, Martha's VineYard; Map, no caption