St Barts or St John?

Both islands are built around their beaches, and the swimming is equally good on each, in warm, clear water all year. The difference is in character. St Barts offers variety in small coves: wild, shadeless Saline and Gouverneur with occasional surf, the calm reef lagoons at Grand Cul-de-Sac, the walk-in quiet of Colombier and the social beach at St Jean under the landing planes.

St John's beaches are mostly protected parkland along the north shore, longer, greener and more natural, with Trunk Bay's snorkel trail and turtles in the shallows at Maho. The trade-off is that the best known fill by late morning in winter, while St Barts' beaches are rarely crowded.

St Barts eats far better. It is French at heart, with proper boulangeries, cheese and wine in the supermarkets, long lunches on the sand at St Jean and Flamands, and polished cooking along the Gustavia harbour, even if nearly everything aims at the same expensive register.

St John is more casual and more limited: open-air grill restaurants, beach bars and food trucks in Cruz Bay, with West Indian dishes such as johnnycakes and stewed goat as the most local flavour. Its fine-dining tier is thin, and most produce is shipped in.

Neither island is a place for sightseeing, though St John has a little more to seek out. Its history sits in the forest: the Annaberg sugar mill, the estate ruins and Taíno petroglyphs on the Reef Bay Trail, and the fort site at Coral Bay where the 1733 slave revolt began.

St Barts has its Swedish legacy in Gustavia, with the clock tower, the Wall House museum and the old forts, plus the church at Lorient and the village of Corossol. It is pleasant, but an hour or two covers it.

St Barts is the island for going out, at least in season. From Christmas into spring, beach lunches at St Jean turn into dancing on the tables, and evenings move on to Gustavia's harbour bars, late clubs and yacht decks, peaking in the loud week around New Year.

St John has no clubs at all, just a few friendly open-air bars on the Cruz Bay waterfront and in Coral Bay, where most nights finish soon after dinner. The catch on St Barts is that much of the scene closes in late summer and autumn.

St John is the stronger choice for nature by a wide margin, because most of it is national park. Steep dry forest runs down to undeveloped bays, a trail network crosses the island to Ram Head and Lameshur, and the reefs at Waterlemon Cay and the seagrass at Maho are full of turtles, rays and coral.

St Barts has lovely views from its hill roads and a marine reserve where turtles are common, plus good kitesurfing in the Grand Cul-de-Sac lagoon. On land, though, the walking amounts to the cliff path to Colombier and a few viewpoints.

St John is better placed for outings. St Thomas, with the Danish streets and fort of Charlotte Amalie, is a short ferry ride away, and day charters cross to Jost Van Dyke, Tortola and the boulders of The Baths on Virgin Gorda, stopping to snorkel at empty cays. Bring a passport for the British side.

From St Barts there is really only the hour-long ferry to St Martin for Marigot, Grand Case and Philipsburg. Anguilla, Saba and St Eustatius are near but need a charter or small plane.

For families the two islands are much alike: very safe, slow-paced and good for children who love the water, but with no attractions built for them. St Barts relies on the calm lagoons at Grand Cul-de-Sac and Petit Cul-de-Sac, Shell Beach and a villa pool, though the open beaches such as Saline can have strong waves.

St John's draw is turtles at Maho Bay in water a child can stand in and the gentle snorkel trail at Trunk Bay. Few of its beaches have lifeguards, and the journey there, by flight, taxi and ferry, is longer.

Both islands mean renting a car and tackling steep, narrow, hairpin roads, but St Barts is a little easier. Its small plane lands on the island itself, and Gustavia and St Jean are walkable.

St John has no airport, so arrival is a flight to St Thomas, a taxi to Red Hook and a ferry, and you drive on the left once there. In its favour, open-air safari taxis run from Cruz Bay to the north shore beaches, which St Barts, with no buses and few taxis, cannot match.

Shopping is one of St Barts' surprises. Because it is duty-free, the streets around the Gustavia harbour hold a dense run of luxury fashion, watch and jewellery boutiques, with resortwear in St Jean and straw work from Corossol.

St John offers a couple of courtyards in Cruz Bay with galleries, local jewellery and hand-painted pottery, which fill an hour. For more, people take the ferry to Charlotte Amalie's duty-free streets.

Neither is a cheap trip, but St Barts sits at the extreme, among the costliest vacation islands anywhere, with no budget side at all beyond cooking in your villa.

St John is expensive too, with high villa rates, shipped-in food and jeep hire, yet it leaves more room to save. The national park beaches and trails are mostly free, and the Cinnamon Bay campground gives a simpler way to stay.

Neither island has a theatre or a concert hall, so performance comes in short seasons rather than as a programme. St Barts has the more refined moment. Each January a long-standing festival brings classical music, opera and dance into the churches and outdoor venues of Gustavia, which gives a winter stay an evening or two of real culture. Its carnival comes just before Lent, with steel bands in the streets.

St John's big event falls in early summer instead. The St John Festival is a carnival of parades, calypso, the islands' own quelbe music and food fairs, and gives a trip outside the winter season something to plan around. For the rest of the year both islands rely on bar music, though the kind differs: DJs and bands in Gustavia's harbour bars in high season, against acoustic sets and the occasional steel pan or reggae group in Cruz Bay.

For a pampering stay, St Barts has the edge. Its luxury hotels run polished spas, and therapists and yoga teachers will come out to a villa. Beyond that, its appeal is an unhurried rhythm on an island without tower blocks or casinos, at its stillest in spring.

St John offers less in the way of treatments, just a few yoga studios, resort therapies and visiting masseurs, but its quiet runs deeper. Because the national park covers most of the land, the hillsides stay dark and nearly empty, and after nightfall you hear frogs rather than cars. It rewards a stay spent reading on a villa terrace and swimming before breakfast, more than one spent booking sessions.