Martinique or Sint Maarten?

Both are first-rate beach islands, and the difference is in the type of beach. Martinique has coves on its Caribbean side: the palm-lined curve of Grande Anse des Salines, the black and gold sand side by side at Anse Noire and Anse Dufour, and the bays at Les Anses-d'Arlet where turtles graze a few metres from shore. Its Atlantic coast is mostly too rough for swimming.

On Sint Maarten the open border puts two countries' beaches within half an hour. You can swim at Mullet Bay, join the crowd at Orient Bay, take the short boat to the reef-sheltered water off Pinel Island, or watch jets roar over Maho. The trade-off is cruise-day crowds at Great Bay and Maho.

Martinique eats better. Its Creole cooking has a clear French influence, with colombo, blaff and accras, and rhum agricole is made under the island's own appellation, which you can taste at the old cane estates. The ti-punch before a meal is a daily ritual, and the covered market in Fort-de-France is worth a morning.

On Sint Maarten the Dutch side mostly offers steakhouses and seafood grills for visitors. The food worth seeking out is on the French side, in Grand Case, at the seafront restaurants and the smoky lolo barbecue stalls, and guavaberry liqueur is the local drink.

Martinique has a real story to tell, and Sint Maarten hardly has one. In Martinique, Saint-Pierre's ruined theatre and the prison cell left by the 1902 eruption make a sobering visit. Add the Empress Joséphine's birthplace at Les Trois-Îlets, the restored sugar estates and the Anse Cafard memorial to enslaved Africans, and there are a few full days of sightseeing, even if no single site is large.

On Sint Maarten, the 1793 Courthouse on Front Street, a small museum and the ruins of Fort Amsterdam and Fort Louis take a morning at most.

Sint Maarten is the island for going out. Simpson Bay and the Maho area have sunset beach bars, late casinos and a few clubs that stay open into the small hours. Grand Case and Orient Bay offer a calmer French-side evening if you want one.

Martinique's evenings usually end with a ti-punch and an early night. The zouk and kompa clubs around Fort-de-France fill with locals at weekends, but they are spread out and you need a car to reach them. The exception is Carnival before Lent, which keeps the towns up late.

The gap here is wide. Martinique's UNESCO-listed north has a real volcano to climb, rainforest along the Route de la Trace, waterfalls and gorges for canyoning. Offshore there are Diamond Rock, the wrecks off Saint-Pierre and the sailing harbour at Le Marin, with dolphins and seasonal whales off the Caribbean coast.

On Sint Maarten, the dry hills of Pic Paradis and Sentry Hill make pleasant short walks. The sea is the better half of its outdoors, with the Man of War Shoal marine park, snorkelling at Creole Rock and Tintamarre, and kitesurfing in Orient Bay.

Sint Maarten is the better base for hopping between islands. Ferries reach St Barths and Gustavia in about an hour and Anguilla in about half an hour from Marigot, and steep little Saba is a longer crossing, with the French half of Sint Maarten itself as an easy extra day.

From Martinique the best day out stays on the island: a tour of the rum estates around Sainte-Marie and Le Robert, or a drive to Grand-Rivière at the end of the north coast road. Fast ferries to Dominica or St Lucia make a long day out, but they are about the only trips off the island.

Both work for families who plan around the beach, but in different ways. Martinique offers calm southern bays where children can snorkel with turtles, plus French healthcare and supermarkets, though the winding drives north can tire small children. Sint Maarten has more ready-made comfort, with resorts that have pools and kids' clubs, short distances, and zip lines and treetop courses for older children. There is little to do anywhere on a rainy day.

On both islands a hire car is close to essential and traffic is the main frustration. Martinique is larger, with steep northern roads and jams around Fort-de-France. Its useful extra is the bay ferry to Les Trois-Îlets and Anse Mitan, which avoids the traffic. Sint Maarten is so small that everything is close, but the causeway and Philipsburg back up on cruise days, and the minibuses run without real timetables.

Sint Maarten has the stronger shopping, mostly because it is a duty-free port. Front Street in Philipsburg suits anyone hunting for a particular watch, piece of jewellery or bottle, and Marigot adds French perfume and fashion boutiques.

Martinique's best buys come from the island itself. You can take home aged agricole rum from the estates, vanilla and hot sauces from the Fort-de-France market, and madras cotton. Beyond that there are only mainland French chain stores.

Neither island is cheap, but Martinique is easier on the budget. Its French prices with an island premium can be softened by renting a self-catering gîte, buying at roadside stalls and taking advantage of the free hiking and low-cost rum tastings.

Sint Maarten costs more. Restaurant meals cost more than their quality justifies because so much is imported, and winter resort rates are steep. Apartments in Simpson Bay, the Grand Case lolos and lower rates in the hurricane season are the main ways to save.

Martinique has more live culture to seek out. Bèlè drum-and-dance evenings in northern villages welcome visitors into the circle, and Fort-de-France has a national arts centre and a July festival, though most of the theatre is in French.

Sint Maarten's high point is its spring Carnival, with calypso, soca and steel pan. Outside that season, music means bands and DJs in beach bars and resort lounges.

Neither island has a bathing tradition, so relaxing comes down to resort spas and the pace of the place. Martinique has a slight edge. Its southern coast slows into swimming and long lunches, a Caribbean-side villa is easy to settle into, and there are warm volcanic springs in the northern forest. On Sint Maarten, real calm means staying near Dawn Beach or on the French side, away from the cruise traffic and the Simpson Bay strip.