Koh Phangan or Koh Phi Phi?

Both islands are built around their beaches, and the water is warm on either. The difference is in the setting. Koh Phangan has a long coastline of varied bays: soft-sand Thong Nai Pan and boat-access Bottle Beach in the north, dependable swimming at Haad Yao and Haad Salad, and the sandbar walk to Koh Ma, though the southern shore is too shallow at low tide.

Koh Phi Phi has fewer beaches but more drama, with clear turquoise water under limestone cliffs. Long Beach and Laem Tong are the swimming beaches, and boat trips add Bamboo Island and the coves of Phi Phi Leh. Busy, shallow Loh Dalum is the one to skip.

Neither island is a reason to travel for food, but Koh Phangan eats better. Thong Sala's evening market and Saturday walking street give a proper spread of southern Thai dishes, and Srithanu's vegan and raw cafés add a health-food scene that Phi Phi has nothing to match.

On Koh Phi Phi, eating means the lanes of Tonsai village, where pizza and burgers sit beside toned-down curries. The highlights are simple: roti from a cart and fresh seafood grilled on the beach in the evening.

Neither island has much to see, though Koh Phangan has a little more. Its temples, Wat Phu Khao Noi and the meditation temple of Wat Khao Tham, and the royal initials carved into the rocks at Than Sadet fill a pleasant afternoon. On Koh Phi Phi the sights come down to a small tsunami memorial and a glimpse of Viking Cave from a passing boat.

Koh Phangan is the bigger party island by some distance. Once a month the Full Moon Party fills Haad Rin's Sunrise Beach with tens of thousands of people, and half-moon and jungle parties run inland in between. Srithanu offers a softer alternative, with sunset bars and sober ecstatic dance.

Koh Phi Phi's nightlife is smaller and the same every night: bucket drinks, fire shows and dance music on Loh Dalum beach, plus reggae bars and amateur Muay Thai in the village. On either island, quiet evenings mean staying well away from the party beach.

Koh Phi Phi has the more striking landscape. Sheer limestone walls rise from the sea, the climb to the viewpoint looks over both bays, and kayaks slip under the cliffs of Phi Phi Leh into Pileh Lagoon. Underwater there are soft-coral walls at Bida Nok and blacktip sharks at Shark Point, though the reefs show the wear of heavy boat traffic.

Koh Phangan's outdoors is gentler: jungle trails to Khao Ra and waterfalls that run fullest after the rains. Its best offshore outings are Sail Rock, a top Gulf dive site, and boat days to Ang Thong marine park.

Both islands rely on ferries, and neither has much heritage within reach. From Koh Phangan, Koh Samui is only half an hour away for the Big Buddha and the old shophouses of Bophut, and Koh Tao makes a snorkelling day.

From Koh Phi Phi, Koh Lanta's old town and Railay's cliffs are an hour or more each way, and Phuket Town makes a long day. Most outings stay local, by longtail to the empty bays nearby.

Both islands work for families only if you pick the right base, and neither has attractions built for children. Koh Phangan's gently shelving northern bays, Thong Nai Pan, Haad Yao and Haad Salad, have family resorts, but the steep roads are full of scooters, and Haad Rin around the full moon is best avoided.

Koh Phi Phi has no cars, which helps, and Laem Tong has calm water and pools. Against that, medical care is basic, the village is noisy late into the night, and the ferry can be rough outside the dry season.

Koh Phi Phi is simpler to get around, because there is so little ground to cover. The village and Loh Dalum are a short walk apart on car-free lanes, and longtail boats or hill paths reach the outer beaches. The catch is the ferry of up to two hours from Phuket or Krabi just to get there.

Koh Phangan is larger and spread out, with no proper public transport. Most visitors rent scooters on steep, sometimes gravel roads where accidents are common, or rely on songthaews and app taxis, and Bottle Beach still needs a boat.

Koh Phangan's shopping is casual but varied. Thong Sala's Saturday walking street sells loose cotton clothes, cheap jewellery and Thai snacks, Srithanu sells yoga wear, crystals and handmade festival outfits, and Haad Rin sells neon party gear. That is a little more range than Koh Phi Phi, whose village lanes sell sarongs, sunscreen, snorkel gear and souvenir T-shirts, plus a few tailor and jewellery stalls. On either island, serious shopping waits for the mainland.

Koh Phangan is the cheaper island, and a long stay in a simple bungalow on the west coast costs very little. Prices rise in the boutique resorts of the northern bays, and Haad Rin rooms jump sharply around the full moon.

Koh Phi Phi is expensive by Thai standards. Everything arrives by boat and space is tight, so dry-season rooms, drinks and longtail rides all add up, and visitors pay an island and marine park fee on top.

There is no theatre or formal stage on either island. Koh Phangan's informal music is a little richer: acoustic and open-mic nights in Srithanu's beach bars, reggae jams, and the music that goes with ecstatic dance and sound healing. On Koh Phi Phi, performance means fire dancers and cover bands as part of a night out.

Koh Phangan is one of Asia's main places to slow down, and Phi Phi does not compete. Srithanu's yoga shalas, detox programmes, breathwork and silent retreats draw people for weeks or months, Wat Khao Tham has long offered Buddhist meditation, and the northern bays are quiet after dark.

Koh Phi Phi has massage everywhere and proper spas at its northern resorts. Rest there depends on staying at Laem Tong or the eastern bays, well away from the noise of Tonsai.