To be correctly termed single malt, a whisky must be made from 100% malted barley, exclusively at one distillery.
However Scottish distilleries will blend from different barrels to achieve a consistent taste and this is still classified as single malt. The age of the whisky must be listed in line with the youngest component.
Australia’s single malt producers are an order of magnitude smaller and younger with less barrels to choose from. As a result, many release their single malt one cask at a time.
Makers of blended whisky can use malt from any number of distilleries giving them much greater flexibility to create a specific taste profile. The producers of the ingredient malts are not listed and sales derive from the brand of the blender.
Another important distinction is that blended whisky does not have to be made from 100% malted barley and grain whisky is often added. This less distinctive spirit is often produced in huge volumes and is why some consider blended whisky an inferior product to single malt.
Most quality Australian whisky is currently produced as single malt. The few blended whiskies that are available tend to be one distillery’s malt mixed with grain whisky. Kinglake Distillery Single Malt is blended between barrels to create as consistent a taste as possible for a very small handmade distillery.