Syrah and Shiraz are two names for the same grape variety, but the wines they make are very often radically different. Syrah produces some of the finest, slinkiest grand vins of southern France. Shiraz powers the beefy, blockbuster reds of southern Australia.

If any grape illustrates the importance of place over grape in winemaking, it's the Syrah/Shiraz. In France, the Syrah has its apotheosis in the elegant, gamey and scarily expensive wines of Hermitage, a one-hill appellation south of Valence in the Rhône Valley. Hermitage is Syrah HQ, and the hill's revered name has been synonymous with this "noble" grape variety for centuries.

The first Syrah vines were taken from France by a Scotsman, James Busby, who settled in New South Wales in 1824 and was to become "the father of the Australian wine industry". In his time, Syrah was better known as Scyras, and the name Shiraz is likely an Australianisation of this.

The vines Busby planted were an instant success, and Shiraz was soon the most widely cultivated black grape variety across the continent, as it still is. In the early days the wines were probably wildly sweet and alcoholic thanks to overripening of the grapes in high temperatures and unremitting sunlight. But the old "hot" and "cooked" Aussie reds of distant memory have now largely been displaced by modern methods in the vineyard and winery.

Nevertheless, Shiraz wines from the Barossa or Hunter valleys of today are still very distinct from their begetters back in France. Take a popular brand such as Peter Lehmann Shiraz 2008 (Waitrose £9.49). It's a sophisticated Barossa red with smooth, cushiony black fruit, weighty with 14.5 per cent alcohol and intensely ripe with chocolate richness at the centre. At four years old, it's quite mature and mellow, but will probably develop for some years yet.

Along the shelf at Waitrose, compare this with Caves de Tain Crozes-Hermitage 2008 at £10.49. This pure Syrah, from a humbler appellation neighbouring Hermitage itself, is a gripping, dark brambly red with smokiness and spice, long, sleek depths and a mild 12.5 per cent alcohol. It is already mellow with age, but might not develop much longer.

The Aussie Shiraz, in short, is a big, friendly red with plenty of life left in it. The French Syrah is a more delicate flower, deliciously complex and interesting, but to drink now before it fades. Of course, every wine is different, but these two do neatly represent the France/Australia gulf.

Which makes it all the more curious that winemakers in both these nations are constantly striving to imitate each other.

While Aussie Shiraz has boomed in sales for a generation, its French counterparts have struggled, especially here in Britain. French growers have successfully petitioned for the use of the name Shiraz in place of Syrah on the labels of their "varietal" wines – those named after the grape variety rather than the vineyard location – in the belief that Shiraz is now more readily recognised, and perhaps better liked. At the same time, Australian producers have been quietly toning down the legendary "up-front fruit" of their monster reds to make subtler, more balanced styles. In Shiraz wines it is now quite common to add a small amount of juice from the white grape, Viognier, to lighten and lift the finished product. This has been standard practice in the Rhône for years.

Are Australians doing it to make their wines taste more French, I once asked Steve Webber, winemaker at the great Yarra Valley producer De Bortoli. "No," he retorted. "It's to make it more feminine."

The rivalry between these two nations provides an endless array of fascinating wines, plenty of them from the Syrah-Shiraz double act. Try one or two of these for size.

St Joseph Cave de St Désirat 2009 (Yapp Bros £11.95) is a pure Syrah from the appellation of St Joseph west of Hermitage. It is thrillingly slinky and juicy, with suggestions of redcurrant, mint and spice amid the intense dark fruit. It will mature on in-bottle for years and years.

Morse Code Padthaway Shiraz 2009 (Tesco £8.99) is a generously ripe red with lifted fruit and easy weight from the relatively cool climes of South Australia. Juicy, spicy, savoury and trim in the way of the new-wave in Aussie winemaking.

Balthazar Syrah Pays d'Oc 2009 (Waitrose £9.99) is a hearty, intense, spicy red from the Languedoc in Mediterranean France. Vin de pays from this region are more usually blends of Syrah with Grenache, Mourvèdre or other varieties, so this one shows what the constituent grape can do without assistance.

Ebenezer and Seppeltsfield Shiraz 2009 (Marks & Spencer £11.99) is almost black in colour, and I thought I detected a whiff of pomegranate in the aroma. From the admirable St Hallett winery in the Barossa Valley, this is a huge, warming and toasty red with a poise all its own.