Cardiff or London?

Neither city is a beach destination, and the real difference is what each can reach. From Cardiff, Barry Island's sandy bay and summer funfair are about half an hour by train, Penarth's pebble shore and pier are closer still, and the surf at Porthcawl and the wide sands of Gower are a drive away. London's nearest sea is Brighton's long pebble beach, an hour out, with sandier shores at Margate and Whitstable on the Kent coast.

London's edge is swimming in the city itself, at the lidos in Brockwell Park and Parliament Hill or the year-round Hampstead Heath ponds. Cardiff's own waterfront at the Bay is tidal and brown, a place for a stroll rather than a swim.

Cardiff eats pleasantly rather than memorably. Its Victorian market, with Welsh cakes off the griddle, cawl and laverbread with cockles, gives you a taste of Wales that London cannot. Pontcanna and Canton have good neighbourhood bistros, and the Middle Eastern and South Asian cooking along City Road adds range. The chain restaurants at the Bay are better for the view than the food.

London is in another league for eating. Its strength lies in the cooking of its communities: Bangladeshi food on Brick Lane, Punjabi in Southall, Turkish grills in Green Lanes and Caribbean and West African cooking south of the river. On top of that come Borough Market, the weekend food markets and a large fine-dining scene. Eating well there is easy, but it rarely comes cheap.

Cardiff fills two or three days well. Its castle sets lavish Victorian Gothic rooms inside Roman and Norman walls, and the National Museum in Cathays Park has a surprisingly strong collection of French Impressionists. St Fagans, an open-air museum of buildings brought from all over Wales, has no real equivalent in London. Little of the city is older than the coal boom, though.

London's collections are among the deepest anywhere. The British Museum, the National Gallery, the V&A and the two Tates are each worth a day, and most are free. Around them stand a thousand years of landmarks, from the Tower and Westminster Abbey to Wren's St Paul's and Greenwich. A week there still leaves much unseen.

Cardiff's nightlife is concentrated and easy to get the measure of. Big weekend groups fill St Mary Street, small alternative bars line Womanby Street opposite the castle, Pontcanna has quieter pubs, and on rugby international days the whole centre turns red. Two nights is enough to see it all, and midweek is quiet.

London works on a different scale, with a separate scene in each district. Soho has late cocktail bars and a long-established gay scene, Shoreditch, Hackney and Dalston have warehouse clubs, and Brixton and Peckham have rooftop bars. Away from the hubs it keeps sensible hours too, but its Friday and Saturday nights are world-class.

Cardiff sits much closer to real landscape. Bute Park leads straight onto the Taff Trail up the valley, and the Wales Coast Path runs past the cliffs at Penarth. In about an hour by car you can be on the ridges of Pen y Fan, the highest ground in southern Britain.

London is remarkably green inside the city, with the deer of Richmond Park, the views from Hampstead Heath and the gardens at Kew. The country beyond is gentle, though: the chalk of the Downs and the beechwoods of the Chilterns, with no mountains. Expect damp weather in both, and wind on the Welsh tops.

Cardiff's day trips are mostly about castles. Caerphilly is twenty minutes by train, Castell Coch stands in the woods just north of the city, and Chepstow pairs with Tintern Abbey in the Wye Valley. Blaenavon and Big Pit add the industrial past, and Bath and Bristol are about an hour away, although some of the best places need a car.

London's position at the centre of the rail network gives a much wider choice. Oxford, Cambridge, Windsor, Canterbury, Brighton and Portsmouth's dockyard are all easy outings, and Stonehenge pairs with Salisbury. A week can include several quite different days without repeating a theme.

Cardiff's strength with children is ease. The centre is flat and compact, and Techniquest at the Bay, the farm animals and old shops of St Fagans and the rowing boats on Roath Park lake make for unhurried days. Barry Island's sands are a short ride away in summer. There is no zoo, aquarium or theme park, however.

London gives children far more to do. There are the dinosaur halls of the Natural History Museum, the Science Museum's hands-on galleries, the pirate ship playground in Kensington Gardens and ZSL London Zoo, with theme parks and the Harry Potter studio tour outside the city. The cost is effort: long distances, Tube stations with only stairs and big crowds when schools are out.

Cardiff is a city for walking. The castle, museum, arcades, market and Central station are minutes apart on flat, largely pedestrianised streets, and a shuttle train or water taxi runs to the Bay. Beyond that there are only local trains and buses, and the national park needs a car.

London's Underground, Elizabeth line, Overground and buses reach almost everywhere on one contactless card, so a car is never needed, and riverboats add the Thames. What you pay in return is distance and effort: long journeys between neighbourhoods, corridors and stairs, and packed trains at rush hour.

Most of Cardiff's shopping is high street, with one real draw. Its glass-roofed Victorian and Edwardian arcades, such as the Royal and the Morgan, are full of independent record, book and vintage shops, and the market sells lovespoons and Welsh blankets. There is no luxury tier, and an afternoon covers it.

London is one of the world's great shopping cities and can fill days rather than hours. It runs from the luxury houses of Bond Street and the tailors of Savile Row to the historic department stores of Knightsbridge and Regent Street. Weekends add the markets of Portobello Road, Camden and Columbia Road.

Cardiff costs clearly less on almost every count. A room that would be cramped and costly in central London is a reasonable night's spend here, meals and pints are at ordinary British prices, and you rarely pay to get around because the centre is walkable. The catch is timing: on big match or concert weekends at the stadium, rooms become scarce and dear.

London charges more for nearly everything, above all a bed near the sights, with eating out and evening tickets close behind. Both cities keep their national museums free, which narrows the gap by day. In London, sleeping further out on a good line, eating at markets and cafés and relying on the daily fare cap make a visit manageable, though never cheap.

Cardiff has a respectable arts life, centred on the Wales Millennium Centre at the Bay, home to Welsh National Opera. It also has the BBC National Orchestra of Wales, student productions from the Royal Welsh College and rising bands in the small venues around Womanby Street. Choral singing gives it a distinctly Welsh note.

London is one of the world's two great theatre cities. It has the West End, the National Theatre, the Globe and fringe stages above pubs, opera and ballet at the Royal Opera House, five major orchestras, and the Proms at the Royal Albert Hall every summer. For a trip built around evenings at a show, there is no contest.

Cardiff has no bathing tradition, so relaxing there means a hotel spa, one of a few day spas or a leisure pool at the Bay hotels. Its easy pace is the real asset: slow mornings in the cafés of Pontcanna and a walk along the Taff through Bute Park.

London offers rather more. It has surviving Victorian and Edwardian Turkish baths under tiled vaults in Bayswater and at Ironmonger Row, full spas in the grand hotels of Mayfair, and cold dips in the Hampstead ponds. For taking the waters properly, people head to the thermal spa at Bath, which is a little nearer to Cardiff.