Kefalonia or Zakynthos?

Both islands have outstanding beaches and equally clear water, but the beaches are of different kinds. Kefalonia's best-known beaches are pebble beaches below cliffs: Myrtos and Petani on the north-west and Paliki shores, and Antisamos near Sami. For sand you head to Skala, Lourdas or Xi, and because these beaches lie on different coasts, a beach vacation here involves a fair amount of driving.

Zakynthos has more sand close together. Laganas Bay, the Vasilikos coves and the shallow north-east coast are all within easy reach, and Gerakas and Dafni are kept undeveloped for nesting turtles. Its most famous view, the wreck at Navagio, is a sight to look at from above or from a boat, and resort sunbeds fill up in high summer.

Both islands eat in Greek tavernas, and each has its own dishes. Kefalonia has a slight edge because of its wine: the Omala valley wineries offer Robola tastings, and Argostoli has a waterfront fish market alongside the meat pie and garlicky aliada. Harbour tavernas at Fiskardo and Assos make dinner the main event of the evening.

On Zakynthos, look for skordostoumbi, ladotyri cheese and Verdea wine in the villages around Keri, because Laganas and Tsilivi lean towards English breakfasts and international menus. Neither island has much fine dining.

The 1953 earthquake left both islands with plain rebuilt towns, so sightseeing is a sideline on either. Kefalonia's sights are spread out: Fiskardo, which survived the earthquake, the Venetian fortress at Assos, the Mycenaean tomb at Tzanata and the deserted village of Old Vlachata.

Zakynthos keeps most of its sights in its capital. The Byzantine Museum on Solomos Square, with its Ionian school icons, the Solomos museum and the castle on Bochali hill make a neat half day in one place.

Zakynthos is far stronger for a night out, though almost all of it is in one place. Laganas in summer is a strip of clubs, promoters and foam parties that goes on until dawn, aimed at young British groups, while the rest of the island is quiet by comparison.

Kefalonia has nothing similar. A late evening there means the Lithostroto in Argostoli, cocktail bars at Lassi or a harbour bar in Skala or Fiskardo. Clubs are few and small, which is exactly why couples who want to avoid the party crowd choose it.

Kefalonia has the richer landscape inland. Mount Ainos rises to about 1,628m and is a national park, with forests of Greek fir and semi-wild horses. Below ground are the Melissani cave lake and the Drogarati chamber, so there is more to do on foot than on Zakynthos.

Zakynthos's scenery is mostly coastal: the cliffs at Keri and above Navagio, the sea caves at Cape Skinari and the Laganas Bay marine park, where turtle-spotting boats go out early. It also has the better diving and snorkelling of the two.

Kefalonia is better placed for trips off the island. Ithaca is a short ferry ride from Sami, with Vathy, Kioni and the sites linked to Odysseus, and in summer boats run from Pessada to Zakynthos and from Fiskardo to Lefkada.

Zakynthos's options are fewer and longer. There is a summer ferry to southern Kefalonia, and a crossing of about an hour to Kyllini on the mainland, from which Chlemoutsi castle is close and ancient Olympia makes a long day.

Zakynthos is the easier island for families. The north-east coast around Tsilivi, Planos and Alykes has calm, shallow water and resort hotels with pools and kids' clubs. There is a water park inland, and because the island is small, no drive is long.

Kefalonia works for families who stay on the south coast at Skala or Lourdas, or at Xi, and children enjoy the boat ride through Melissani. But it has no attractions built for children, and the long, winding drives in summer heat make each day out harder.

On both islands you really need a car, but Zakynthos makes it a little easier. It is only about 40km long, buses reach the main resorts, taxis are easy to find, and boat excursions cover many of the beaches and caves.

Kefalonia is larger and more mountainous. Argostoli to Fiskardo takes about an hour and a half on ridge and cliff roads, buses run too rarely to plan a day around, and the summer ferry across the bay to Lixouri is a useful short cut.

Neither island is a place to shop. On both, the best things to take home are honey, olive oil, local wine and almond sweets, mandoles on Kefalonia and mantolato nougat on Zakynthos. Kefalonia adds the small boutiques around Fiskardo's harbour, while Zakynthos has village lace and weaving around Volimes.

Zakynthos is the cheaper of the two, mainly because package tourism keeps room prices in its big resorts moderate even in summer. Boat trips and sunbeds still add up over a week.

Kefalonia costs a little more. Apartments around Skala, Lourdas and Lassi are fair value, but Fiskardo and Assos, with their yachting crowd, are expensive, and car hire is close to unavoidable. On both islands June and September are cheaper than high summer.

The two islands are alike here: both share the kantades serenade tradition and an old philharmonic band, and neither has a theatre or concert season. On Kefalonia you are most likely to hear music at summer open-air concerts in Argostoli's squares. On Zakynthos the songs turn up informally in town and village tavernas, and at carnival villagers perform omilies, a traditional folk street theatre.

Neither island has a spa culture beyond the hotels, so rest on both comes from a slower pace. Kefalonia makes that a little easier, because it has no party zone to steer around, and the Paliki peninsula, the north-east coast and evenings in Assos are quiet by default.

On Zakynthos, calm depends on where you stay: the hill villages around Keri, the Vasilikos peninsula or the small northern harbours, well away from Laganas. In return it has the cool sulphur springs that bubble into the sea at Xigia.