Formentera or Ibiza?

Both islands have clear water over seagrass meadows, but Formentera's beaches are a step ahead. They are the whole point of the island. Ses Illetes runs out towards Espalmador with shallow turquoise water on both sides, and the long south coast at Migjorn has kilometres of sand and dune to spread out on.

Ibiza has more variety, laid out as a chain of coves. There are sandbars at Cala Comte, the long sand of Ses Salines and quiet pine-backed inlets in the north. Its best-known coves fill early in high summer, which is less of a problem on Formentera's longer beaches.

Ibiza eats better. Its inland country restaurants serve sofrit pagès and bullit de peix, and meals end with a glass of hierbas. There are also polished dinners in the marina and Dalt Vila, though the resort strips are weak.

Formentera's cooking is narrower and almost all about the sea. You get grilled catch, lobster stew and the sun-dried fish of the ensalada payesa at beach restaurants above Migjorn. Beyond those long lunches there is little, and many kitchens close outside summer.

Ibiza has far more to see. Dalt Vila is a UNESCO-listed walled town, and its ramps and bastions climb to the cathedral and castle. The Phoenician necropolis of Puig des Molins lies below it, and fortified white churches such as Puig de Missa stand around the island.

Formentera's sights are few and simple: the fortified church in Sant Francesc, the lighthouses at Cap de Barbaria and La Mola, the Bronze Age tomb at Ca na Costa and the remains of a Roman fort. Together they make a pleasant detour between beaches rather than a reason to go.

Ibiza's clubs are among the best known in the world. They run every night from late spring to early autumn, with famous DJ residencies along Platja d'en Bossa and near Sant Rafel. Many parties go on until after sunrise, and Sant Antoni's West End and the boat parties fill the hours in between.

Formentera is the opposite. A night out means sunset drinks towards Cap de Barbaria, a few late bars on the seafront at Es Pujols and an early night. Anyone staying there who wants the clubs has to cross to Ibiza and plan around the ferry back.

The two islands are broadly level for nature, with the same dry landscape of pine and juniper and the same clear water for snorkelling and diving. The difference is in the terrain. Ibiza has the more dramatic coast, with cliffs around Cala d'Hort facing the rock island of Es Vedrà and coastal paths along the north and west.

Formentera is flatter and gentler. It has green cycling routes across the whole island, flamingos on the Estany Pudent lagoon and the cliffs of La Mola as its only high ground.

Each island's main day trip is the other one, about half an hour apart by ferry. From Formentera, Ibiza adds a walled old town, hippy markets and a north coast worth a hired car. A boat out to the empty islet of Espalmador makes a shorter outing.

From Ibiza, the day out is Formentera's beaches by bike or scooter. Ibiza also has its own white inland villages, such as Sant Carles and Santa Gertrudis, to fill a day without taking a boat.

Both islands suit families who want a beach vacation, and neither has a zoo, aquarium or theme park. Formentera is smaller and calmer, with shallow water at Ses Illetes and flat routes that older children can cycle. Getting there means a ferry after the flight, and its beaches have little shade.

Ibiza is easier to reach and has calm, shallow resort bays around Santa Eulària, Es Canar and Cala Bassa. Glass-bottom boat trips are one of its few attractions made for children. Families should steer clear of the party areas.

Ibiza is easier to get to and around. Its airport connects to buses that reach the main towns and beaches, night buses run to the clubs in summer, and water taxis link some resorts. The rural north still needs a car, though, and the summer roads around Ibiza Town get congested.

Formentera has no airport, so everyone arrives by ferry at La Savina. Once there, the island is only about 20km long and almost flat. A hired bicycle or e-bike does most of the work, with one bus line as a backup.

Ibiza has more shops, though it is still not a shopping destination. Boutiques in the marina, below Dalt Vila and in Santa Gertrudis sell the island's loose white linen and boho fashion. The hippy markets near Es Canar and Sant Carles add jewellery, leather and crafts.

Formentera has a few linen and jewellery boutiques in Sant Francesc and an evening craft market in Es Pujols. Its one real draw is the artisans' market at El Pilar de La Mola, where local makers sell leather, ceramics and silver.

Both islands are expensive in summer. Formentera is if anything slightly harder on the wallet, with few rooms, resort-priced beach restaurants and the ferry and bike or car hire on top. Self-catering and going in early summer or late September are the only real ways to save.

Ibiza costs a lot in other ways, with club entry, drinks and late-night taxis. It does have more ways to cut costs: apartments in the east coast resorts, simple country restaurants, the bus network and its many free coves.

Neither island is a place for theatre or concerts, but Ibiza has a little more to offer. It has open-air summer concerts, occasional flamenco evenings, jazz on bar terraces and folk dancing in traditional dress at village festivals. Formentera's live music comes down to musicians at the La Mola market, sunset sets at beach bars and the odd small festival.

Ibiza is the better choice for a restful stay with treatments. The farmhouse hotels among the almond and olive groves around Sant Joan and Santa Gertrudis have a long tradition of yoga and holistic retreats going back to the hippy years. The island's hotel spas are good.

Formentera relaxes you through its slow pace rather than its facilities. The island is low-rise and quiet, and the days are spent between the sea and a long lunch. The spas are small, and yoga and massage are mostly a summer offer.