Here at the very top of the Florida Keys, an hour's drive from Miami, is where you find out the difference between just plain rich and really, really, really rich.

Drive along the little blacktop three miles north from the Card Sound Bridge. At the end of Key Largo the signs stand out, unpretentious and elegant. Ocean Reef Club on the right, members only. Key Largo Anglers Club on the left, members only.

Both are exclusive yachting, fishing and recreation retreats. But what a difference -- the classic difference between nouveau and old-o.

They have a gate with a guard at the entrance to Ocean Reef. You have to have a card to get by it. There's no gate leading into Key Largo Anglers. Who needs one? An outsider would be spotted in a minute. Key Largo members ooze class.

Which means they don't have to show off.

"Are you sure this is the right place?" said my friend Mitch as we drove down the curving driveway into the Anglers Club, between flowering shrubs and a small, par-3 golf course of scorched grass.

There were a few cars parked under fruit trees by the main building, which houses the dining room. No Mercedeses or Cadillacs, just some fairly new Plymouths and Pintos.

The building was neat and trim, but oviously 30 or 40 years old and never modernized.

Inside was all the proof we needed. Along the ledge below the ceiling of the big reception were strung the yachting flags of some members.

Auchincloss. DuPont. Hoover (as in president). Hoover (as in vacuums). Ford (as in motors). Kinickerbocker. Payson. Choate. Kimberly (as in Clark). Van-Clief.

We stood briefly in awe of these grand names and of the power and wealth that attaches to them. Then we took another look around and began to appreciate the trappings of the truly well-to-do.

No shows here. No flash. No chrome or Danish modern.

No gimmicks or gadgets or gimos. The old bar is tiny, with funny pink lights in the ceiling, obviously left over from an interior decorating debacle of the '40s.

But things don't change at Key Largo Anglers. Who would want them to? "We tried to modernize the bar some years back, but the members raised such a fuss the work had to stop," said our host.

Outside on perfect, clean, concrete docks huge motor yachts lay at rest in the dusk. There was no noise from them, no shrieking kids or grease-encrusted mechanics revving balky motors.

For transportation in the compound the members rode fat-tired old bicycles, waving as they passed their fellows.

The orange trees were laden with fruit, as we the kumquat and lemon trees. No one is around with the need to steal. "Want some?" said our host. t"Take as many as you like."

Silence. Solidness. A simple, stately and elegant place.

Across the street lies new blood. Ocean Reef where the talk is busiest when Bebe Rebozo or former president Nixon come to visit.

Ocean Reef has plenty of flash.

The place is crowded with asphalt parking lots.The Continentals battle the Mercedeses. To get around, the members own or rent golf carts, whizzing silently by at busy rates of speed with giddy grins. "We even have some Rolls-Royce carts that cost up to $6,000," someone bragged.

The docks stretch endlessly, crammed with sparkly plastic Hatterases and Chris Crafts.

There are dining rooms and bars scattered about, and no one pays for anything. It all goes on the bill. The cheapest rooms at the motel are $90 a night, with a view of the parking lot.

All this makes it sound worse than it is. Ocean Reef is a fine place on a grand piece of land, with a multitude of golf courses and other things to do.

It just loses by comparison to the place across the street. So who can compete with the guys who wrote the book?