Old World (OW)
Old World countries are usually those with a long history of grape-growing, which includes most of Europe and countries such as Georgia, which is believed to be the birthplace of winemaking.
New World WORLD (NW)
New World countries are usually those which have come to grape cultivation later, such as Australia, New Zealand, USA, South Africa, Argentina, Chile – and very recently, China and India.
What this means
A key difference concerns regional (OW) vs varietal (NW) labelling. Sancerre, for example, is a small village in the Loire, France where, legally, only the white grape Sauvignon Blanc is allowed-but the village, rather than the grape, is what is indicated on the label. On the other hand, Sauvignon Blanc is often the first thing you’ll notice on a New Zealand label where wines are labelled by variety: a practice which becomes a fundamental guide as to what a wine might taste like.
European practices are subject to years of history and dozens of rules which dictate what information is and isn’t allowed on the label. The NW, however, is far freer.
Apart from grape variety, climate also influences wine style. While NW wine regions generally enjoy more consistent weather year-on-year, there are, of course, warmer regions in the OW (think of Sicily vs Bordeaux) and cooler regions in the New World (think of Tasmania vs South Australia). So regionality as well as grape variety are important in both the NW and the OW.
Cooler climate wines tend to be leaner and tighter with more restrained fruit; while warmer region wines tend to be more juicy with grapes almost baking under the heat of the sun.