Atlantic City or Las Vegas?

This is the biggest gap between the two. Atlantic City is a seaside resort above all. Pale, flat sand runs under the Boardwalk for the full length of Absecon Island, it is free and lifeguarded, and the open Atlantic is good for swimming in July and August, between the flags because of the surf.

Las Vegas has no sea at all. Its swimming is in the resort pools, some with sand-edged wave pools, and at Boulder Beach on Lake Mead, a gravel shore with no shade. That is pleasant in the heat, but it does not replace an ocean.

Las Vegas eats on a bigger and more ambitious scale. The Strip gathers famous-chef dining rooms, steakhouses and tasting menus. The long run of Asian restaurants on Spring Mountain Road, many open late, is the best eating in either city.

Atlantic City's casinos offer a smaller version of the same resort dining. What it has and Las Vegas lacks is local food: the Italian-American restaurants of Ducktown, subs on soft rolls, crab shacks on the back bays and saltwater taffy on the Boardwalk.

Neither city is a destination for heritage, and each fills about a day. The difference is in kind. Atlantic City's sights tell the history of the American seaside: the original Boardwalk of 1870, the Art Deco Boardwalk Hall with its giant pipe organ, the Absecon Lighthouse, and Lucy the Elephant in Margate.

Las Vegas offers spectacle rather than the past: the themed resorts, the fountain show and the light canopy over Fremont Street. Downtown it adds two good museums, the Neon Museum's yard of old signs and the Mob Museum in the former courthouse.

Las Vegas is in another league after dark. Well-known DJs hold weekend residencies, dayclubs fill the afternoons and you can carry a drink along the Strip. On a Saturday the crowds are as thick at three in the morning as at nine in the evening, and Fremont Street and the arts district add cheaper dive bars and craft beer.

Atlantic City has the same all-night casino bars, with clubs and pool parties on summer weekends and beach bars on the sand. There is little street life between the resorts, though, and things go quiet midweek and in winter.

Las Vegas has the more striking outdoors, as long as you have a car and avoid the summer heat. The sandstone cliffs and climbing of Red Rock Canyon are half an hour away, the red rock and petroglyphs of Valley of Fire about an hour, and Mount Charleston has pine forest and cooler trails at altitude.

Atlantic City's nature is flat and gentle. There is birdwatching across the salt marsh at the Forsythe refuge, kayaking and crabbing on the back bays, and canoeing in the Pine Barrens. It is good for a morning but not a reason to come.

Atlantic City has far more within reach. Philadelphia, with Independence Hall and its museums, is about an hour and a half by train, and Cape May's Victorian streets are an hour south. The boardwalks of Ocean City and Wildwood, colonial Smithville and the ironworks village of Batsto fill in the gaps.

Las Vegas has Hoover Dam and Boulder City for a half day, and little else nearby. The trips to the Grand Canyon, Zion or Death Valley are long days of driving to see landscape, not a varied set of outings.

Both cities are built around adults and casinos, but Atlantic City works better with children because the beach does most of the work. Add the fairground rides on a pier over the ocean, a small aquarium and Lucy the Elephant to climb, and the family boardwalks of Ocean City and Wildwood are nearby.

Las Vegas can fill a day or two with an indoor amusement park, a shark aquarium and the Discovery Children's Museum. Still, walking routes through casinos, adult advertising and the summer heat wear families down.

Both are simple along one main strip and awkward beyond it, and both need a car for the countryside. Atlantic City's Boardwalk is one level line beside the sea, with jitneys running along Pacific Avenue around the clock and trains to Philadelphia.

Las Vegas is bigger and more deceptive. Resorts that look side by side can be a long walk apart over footbridges and through casinos, and the summer heat makes walking hard, so most visitors use taxis, the monorail or buses.

Las Vegas is the better place to shop. Its resort malls hold the major fashion and jewellery houses, there is a large department-store mall and two big outlet centres, and all of them stay open late.

Atlantic City has one open-air outlet district, gift arcades in the casinos and souvenir stands on the Boardwalk. Neither city has markets or local designers, but Atlantic City's saltwater taffy and fudge are at least something you can only buy there.

Both follow the same pattern: cheap rooms midweek, steep weekend rates and resort fees on top. Atlantic City comes out cheaper because so much is free, including the beach, the Boardwalk and the summer concerts, and subs and boardwalk pizza keep meals cheap.

Las Vegas costs more once you are inside, with cocktails, club entry, shows and dining on the Strip all expensive. Eating in Chinatown and staying downtown help, but it is rarely a budget trip.

Las Vegas is one of the world's great show towns. Permanent theatres put on water and aerial spectacles, magicians and revues every night, and big stars hold long residencies. The Smith Center adds touring Broadway musicals, the Philharmonic and ballet.

Atlantic City has touring headliners, comedians and tribute acts in the casino showrooms, big concerts in Boardwalk Hall and free beach concerts in summer. It has no permanent productions to compare.

Neither city is restful, but Las Vegas does pampering on a much bigger scale. Its resort spas are among the largest in the country, with thermal circuits, salt and ice rooms and day passes for non-guests, and the non-gaming hotels make a calmer base. Atlantic City's casino spas are smaller, and its real calm is the empty Boardwalk by the grey sea in winter.