At first sight these two parts of northern France are similar. Britons liken them both to sunnier and less crowded versions of our own west country, with agricultural roots and strong culinary traditions, sandy beaches and rocky cliffs, and beautiful and historic inland areas with fewer cities than elsewhere in the country.
But similarities between Normandy and Brittany end when it comes to property. Normandy is typified by steeply pitched roofs on half-timbered manor houses; in Brittany, classic older houses are a little denser and use more granite and slate. Their locations vis-à-vis the main ferry ports make them different, too.
"I have a three-and-a-half-hour journey door to door," says the Kent interior designer Louisa Hynes, who in 2003 bought a Victorian seaside holiday home in a Normandy hamlet between Dieppe and Le Havre.
"Like most of Normandy it's incredibly French - no English voices. The British get off the ferries, hit the motorways and miss the place. Brittany is like another planet. It's a long drive from the ports and has a lot of British," says Hynes. She was so inspired by her cottage that she set up Normandy Homefinders, an agency to help buyers relocate or find a second home in the region.
Normandy remains fantastically accessible - it contains the ports of Cherbourg, Caen and Le Havre, although cheap properties close to these towns have long been snapped up. Parisians rival British buyers in many areas, too, although French families avoid renovation projects so there is less competition for these properties.
Hynes says a buyer wanting a Normandy renovation project should expect to pay £50,000 to £60,000 for a barn or farmhouse needing another £30,000 of work to bring it up to a good standard. Those wanting a three- or four-bedroom country house without the hassle of carrying out renovation work should expect to pay about £100,000.
On the other side of the northern French fence is Chris Slade, who six years ago bought a holiday home at Loudeac, central Brittany.
"You get more bangs for your buck in Normandy but Brittany's well known and more popular. We prefer the topography and geography of Brittany - the buildings look more French. The motorways are more or less free and relatively deserted," says Chris, whose main home is in Sussex.
Brittany's homes are dear on the western coast, near Quimper and Bénodet where views and weather add 20 per cent to prices. Dinard and St-Malo are elegant and expensive, too. At Roscoff, Vannes and in much of the Argoat interior, prices are cheaper.
Chris Slade, too, now runs a property agency - A Home in Brittany - to help British buyers, although his rivalry with Normandy has a personal edge. His wife, Micki, has set up a complementary service called A Home in Normandy.
"In both areas there's a surprising number of renovation projects. Agents have to work harder to find them these days, but they still exist," says Chris.
Prices in Normandy and Brittany are roughly stable now but each region has seen a 30 per cent price rise over the past three years - despite budget airlines making southern France, Italy, Spain and even eastern Europe more accessible.
Northern France has escaped the new developments and second-home resorts further south, but that may be about to change. The UK estate agent Savills is selling homes at a resort close to uber-fashionable Deauville, the Normandy version of Brighton famous for a quintessentially French combination of elegant architecture, marinas and casinos.
The resort has pools, spas and golf - facilities more commonly found on the Cote d'Azur. Savills says the homes will be available on a sale-and-leaseback basis with rent guarantees.
"The same developer has created a similar resort in Brittany so these are starting to be seen in northern France. They have been popular in the south but their arrival in Brittany and Normandy shows that international buyers are now interested in these areas," says Sarah Rothschild, a Parisian selling the properties in the UK for Savills.
But for many, the region's primary attractions remain its convenience and the chance to buy a historic home at a relatively cheap price. But the quandary is, Brittany or Normandy?
Head to head
Hot spots: Quimper, Dinard
USPs: 1,200km of Atlantic coastline and the region has its own language
Regional cuisine: Oysters, galettes, salted butter
Must-see: The historic capital of Rennes, and the traditional Fêtes des Filets Bleus held at Concarneau each August.
Hot spots: Honfleur, Deauville
USPs: Second World War beaches, and spectacular landscape of "Swiss Normandy", to the south of Caen.
Regional cuisine: Camembert, Calvados, Dieppe sole
Must-see: Mont St-Michel and the Bayeux Tapestry.