Bora Bora or New Caledonia?

Bora Bora edges ahead for sheer ease. The lagoon is warm in every month and starts at the foot of your bungalow ladder or on the sand of a resort motu, so swimming takes no planning at all. Matira Point at the southern tip is the one long public beach, a curve of soft white sand with shallows that run far enough out for toddlers to paddle.

New Caledonia's water is just as clear, but its best sand is spread out. In Nouméa, Anse Vata and the Baie des Citrons are handy town beaches. The ones worth the long flight need another flight or a ferry: Kanumera and the Oro pool on the Isle of Pines, or Ouvéa's single beach of about 25km. The southern winter takes the edge off the water's warmth, and in summer swimmers keep an eye on cyclone and shark warnings.

New Caledonia eats better, mostly because Nouméa is a real town. It has bakeries, French bistros and lagoon seafood including the farmed blue prawns, plus Vietnamese and Indonesian snacks around the Port Moselle market. Bougna cooked on hot stones at a tribal homestay is a meal worth planning a day ahead for.

On Bora Bora you eat mostly in your resort's few dining rooms. The French-Polynesian cooking can be very good, and poisson cru from a food truck near Vaitape is a highlight, but after a week the choice starts to feel narrow.

Bora Bora has a few restored marae and rusting wartime guns above the lagoon, which fill a few hours on an island tour. New Caledonia has far more to understand: the Tjibaou Cultural Centre, Renzo Piano's wooden shells based on Kanak great houses, the Museum of New Caledonia, and penal-colony ruins on Nouville and the Isle of Pines. Neither is a museum trip, but in New Caledonia two or three days of sightseeing are well spent.

Neither is a place for a big night out, but New Caledonia at least has one. Nouméa's waterfront at the Baie des Citrons and Anse Vata has sunset beach bars, and on Fridays and Saturdays a few bars and small clubs stay busy past midnight. On Bora Bora the evening is a cocktail at your resort bar, a long dinner and an early night.

Both are at their best on the reef. Bora Bora's appeal is the view of Mount Otemanu above a ring of palm-covered motu, with stingrays and blacktip sharks in the shallows and manta rays in the passes. On land, though, there are only the 4x4 tracks and a guided climb up Mount Pahia.

New Caledonia offers more. Its lagoon is a UNESCO World Heritage Site, with dugongs, turtles and humpback whales from about July. Grande Terre also has its own country for walking and kayaking: the red earth and kauri trees of Blue River park, Prony Bay, and the rainforest and waterfalls around Hienghène.

From Bora Bora, a day away means a boat or a flight to Tahaa's vanilla and pearl farms, the sacred marae of Taputapuatea on Raiatea, or quiet Maupiti, all of them small villages, and most visitors never go. Nouméa gives you more choice, and a hire car opens some of it: Bourail and Fort Teremba up the west coast, the convict village at Prony, or a day flight to the Isle of Pines. Even so, these are mostly islets and countryside rather than other towns.

New Caledonia is easier with children. It has shallow, calm bays in Nouméa, the Aquarium of the Lagoons, a forest park where children can see a kagu and lifeguarded islet beaches. Supermarkets and pharmacies are always close, which makes for an easy week.

Bora Bora's lagoon is just as gentle, and the Matira shallows are ideal for toddlers. But the resorts are built for couples, some overwater decks are risky for children who cannot swim, and there is little else for children to do. It suits older children who love snorkelling best.

A small island and a large territory make for very different travel. On Bora Bora the main island's coast road is short enough to ride round in a day by bicycle or scooter. If your resort is on a motu, though, every trip to Vaitape or Matira depends on the hotel's boat, and lagoon outings are mostly organised tours.

New Caledonia needs a hire car once you leave Nouméa, where buses reach the beaches but taxis do most of the work. The east coast is several hours away over the mountains, and the Isle of Pines and the Loyalty Islands add a domestic flight or a fast ferry, then a scooter or a lift from your lodging once you arrive.

Shopping on Bora Bora means black pearls in the Vaitape showrooms, plus pareos and shell jewellery at the stalls on the quay, which take a morning at most. Nouméa has a little more range, with French boutiques, swimwear and duty-free shops and the Port Moselle market. It also has Kanak carvings, vanilla from the Loyalty Islands and sandalwood to take home.

On Bora Bora most of the budget goes on where you sleep and on what comes with it. The room over the water is the main cost, and after that every meal in the resort, every boat across to the main island and every outing on the lagoon adds to it. The island is small, so there are few ways round this. A family-run guesthouse on the main island and cooking from the Vaitape grocery stores cut the bill, but then you give up the overwater stay that brings most people here.

New Caledonia is expensive too, because most goods are shipped in, but the money goes on different things. You pay for hire cars and domestic flights to reach the islands rather than for one luxury room. That leaves more room to save. A tribal homestay or a simple bungalow on the Isle of Pines or the Loyalty Islands, with food from the supermarkets and market in Nouméa, makes a two-week trip far easier to afford than a week on Bora Bora.

Live performance is thin in both, though New Caledonia has a little more. The Tjibaou Cultural Centre stages Kanak dance, theatre and concerts, Nouméa has a modest theatre and a few live bands, and kaneka, the reggae-tinged Kanak music, is heard at festivals. On Bora Bora it comes down to resort dinner shows of drumming, fire dancing and ori tahiti, which are at their best during the Heiva contests in July.

Bora Bora gives you rest in one concentrated form: your resort's spa, Polynesian massage with monoi and tiare, and a bungalow you hardly need to leave. For a couple who want a week of pampering in one place it has more polish, though once you have tried your own resort's spa there is nowhere else to go looking.

In New Caledonia, rest is plainer and more spread out. You find it by staying on the Isle of Pines, Ouvéa or Maré, where the day comes down to shade, a book and the lagoon, with resort massages using niaouli and tamanu oils. It suits travellers who unwind through simple island life rather than a spa menu. The one thermal spring, at La Crouen on the east coast, is too remote to plan a stay around, and Nouméa feels more like an ordinary town than a retreat.