San Diego or Tijuana?

San Diego has the real beaches. There is Coronado's wide sand, the boardwalk shared by Mission Beach and Pacific Beach, gentle surf for beginners at La Jolla Shores and the cliff-backed beaches of North County. The water stays cool all the same, and morning cloud can hang over the shore into early summer.

Playas de Tijuana is a promenade for a walk and a seafood lunch beside the border fence rather than a place to swim, because runoff spoils the water near the city. A proper beach day means driving to Rosarito, where the sand is wider but the sea is just as cold as at Coronado.

Both cities eat in the Baja style, but Tijuana does it at the source and with more depth. Adobada carved from the spit, birria served with its broth and seafood carts piled with sea urchin and clams go beyond San Diego's taco shops. The Baja Med restaurants in Zona Río and Chapultepec also give Tijuana a level of serious dining that San Diego, a city without famous chefs, does not have.

San Diego answers with range and beer: the Korean, Japanese and Vietnamese kitchens of Convoy Street, Little Italy's market and one of the densest craft-brewing scenes in the country. Tijuana brews too and pours Valle de Guadalupe wine, but its cooking rarely goes beyond Mexican, apart from its Chinese-Mexican tradition.

San Diego has more to see. Balboa Park's exposition buildings hold a full day of museums, and the USS Midway and the Maritime Museum's sailing ships line the waterfront. Old Town and Mission San Diego de Alcalá keep the Spanish and Mexican past visible.

Tijuana's sights fit into a day or two. There is the Museo de las Californias inside the domed cultural centre and the Moorish-style Jai Alai palace on Avenida Revolución. Most memorable of all is the border fence at the beach, painted with murals. It is a young city, and its history lives more in stories than in buildings.

Tijuana has the livelier nights out. Avenida Revolución still plays its Prohibition-era role of loud bars for visitors from the north, but the better nights are in the cantinas and small dance spots of Calle Sexta and the cocktail bars of Zona Río, and weekends run late. After dark, stay in these areas and use ride-hailing.

San Diego is easier and finishes earlier. There are rooftop bars and clubs in the Gaslamp, a student bar strip in Pacific Beach, and taprooms and cocktail bars in North Park and Hillcrest, which is also the centre of the city's gay nightlife. Away from the Gaslamp and the beach, the city goes quiet well before last call.

San Diego is an outdoor city. It has the clifftop trails of Torrey Pines, sea lions and kayak routes into the sea caves at La Jolla Cove, tide pools at Cabrillo and surf breaks all along the coast. About an hour inland are pine-forested mountains, and beyond them the canyons of Anza-Borrego.

Tijuana itself spreads over dry, built-up hills with few parks. Its outdoors lie down the coast: the cliff road to Ensenada, the surf near Rosarito and gentle walks among the vineyards of the Ruta del Vino. Serious hiking is too far away for a day trip.

The two share a border and much of the same list of outings, seen from opposite sides. From San Diego, the appeal is variety. You can visit Temecula's wineries, the apple-pie town of Julian in the hills, the beach towns up the coast by train and Los Angeles beyond them, with Tijuana itself a trolley ride away.

From Tijuana, the outings run south and are closer. Rosarito and the lobster village of Puerto Nuevo are about half an hour away, with the Valle de Guadalupe and Ensenada's fish market further on. The real difference is the border: heading south is quick, but getting back into the United States can take hours.

For children, the gap is wide. San Diego has one of the world's great zoos in Balboa Park, the open plains of the Safari Park, SeaWorld, Legoland, and an aquarium and science centre for cooler days. The mild weather and casual style make outings easy, and the main effort is driving between the big parks.

Tijuana has hands-on science at El Trompo, the IMAX dome and the small animal collection at Parque Morelos, and its restaurants are warm towards children. Beyond that, it is a city built for adults and cars, and the attractions families want lie across a border queue.

Neither city is easy without a car, but San Diego is a little better served. The trolley links downtown, Little Italy and Old Town with the border, coastal trains reach the beach towns, and the centre is easy on foot. La Jolla, the beaches and the theme parks still mean hiring a car or using ride-hailing.

In Tijuana, only downtown and Avenida Revolución, close to the San Ysidro crossing, are walkable. There is no metro and the shared route taxis are hard for a visitor to follow, so people rely on ride-hailing and yellow taxis to cross a hilly, spread-out city.

San Diego has more choice, though little you could not find elsewhere. Fashion Valley has luxury brands, a large outlet centre sits by the border, and Little Italy and North Park have independent and vintage shops. La Jolla's village streets lean towards galleries.

Tijuana's shopping is about crafts and food rather than fashion. You can bargain for pottery, silver and blankets near Avenida Revolución, buy chillies, vanilla and tamarind sweets at Mercado Hidalgo, and browse the galleries and record shops in Pasaje Rodríguez.

Tijuana costs far less. Street tacos, seafood carts, hotels in Zona Río and ride-hailing all leave money in your pocket. Only the tourist bars on Revolución, the better Baja Med restaurants and the wine-country tastings come close to prices in the north.

San Diego is expensive across the board, from hotels near the beach to meals with tax and tip added, and admission to the zoo, SeaWorld and Legoland, plus a hire car to reach them. Free beaches, the gardens of Balboa Park and taco shops help keep a day's spending down, but it never feels cheap.

San Diego has the stronger stage. The Old Globe in Balboa Park and the La Jolla Playhouse are producing theatres that have sent shows to Broadway. The symphony plays summer evenings on the bay, and the opera adds a short season downtown.

Tijuana's centrepiece is the concert hall at the Centro Cultural Tijuana, home to the Baja California orchestra, along with a local opera company known for an open-air performance each year in a working-class neighbourhood. The rest is informal and local: norteño bands in cantinas, mariachis at Plaza Santa Cecilia, and the Nortec sound in the bars around Calle Sexta.

Neither city has a bathing tradition, but San Diego is far easier to unwind in. Resort spas in La Jolla, Coronado and Carlsbad, the yoga culture of Encinitas and slow beach-town mornings suit a restful trip.

Tijuana is loud and full of traffic, and its large health trade is medical and dental rather than restful. Visitors looking for calm leave the city for the quiet vineyard estates of the Valle de Guadalupe.