Rum and whiskey are two of the world’s most popular spirits. They are both strong drinks with a complex flavor profile and delicious aroma.

However, although they have a similar appearance, these spirits do vary greatly in terms of ingredients and taste.

In this guide, I’ll explain how rum and whiskey are made along with the key differences between these spirits.

What is Whiskey?

Whiskey is a distilled spirit made from a fermented grain mash. The location of the distillery, the distillation method, and the types of grains used, will determine the type of whiskey produced.

All whiskey is aged in wooden barrels after distillation to improve its flavor. The most common types of whiskey are:

  • Scotch whiskey
    Mashed/fermented/and distilled in Scotland, distilled using pot stills, matured in oak casks, and bottled at no less than 40% ABV.
  • Irish whiskey
    Made from a mash of malted cereals (with or without whole grains), distilled in Ireland (usually in column stills), matured in wooden casks, and bottled at no less than 40% ABV.
  • Bourbon whiskey
    Made using a mash that consists of at least 51% corn and aged in new charred oak barrels. Whiskeys labeled Kentucky or Tennessee bourbon whiskey must be made in those locations and adhere to additional specifications.
  • Corn whiskey
    Made with a mash containing at least 80% corn. Corn whiskey can be aged or not aged. If the whiskey is aged it will use charred or previously used barrels.
  • Rye whiskey
    American rye whiskey must be made from a mash that consists of at least 51% rye. Canadian rye whiskey is a historical classification and may or may not contain rye.
  • Wheat whiskey
    Made using a mash that consists of at least 51% wheat.

In addition to these different types of whiskey, there are sub-categories including:

  • Malt whiskey
    Made using 100% malted grains (a malted grain has been steeped in water and germinated before drying). A single malt whiskey uses one type of grain and has only passed through a single distillery. A blended malt whiskey contains a mixture of whiskeys from different distilleries.
  • Grain whiskey
    Uses a combination of malted barley and unsalted grains.
  • Blended whiskey
    Whiskey that is blended from a combination of grain and malt whiskeys.
  • Cask strength
    A normal whiskey might have some water added to it during the bottling process, to obtain the correct ABV. A cask strength whiskey will not be diluted and goes straight from the cask to the bottle.

What is Rum?

A bottle of mount Gay rum on the beach

Rum is a distilled spirit created from sugarcane byproducts like molasses and sugarcane juice. It is produced using similar processes to whiskey, including fermentation, distillation and maturation. There are several types of rum including:

  • Light rum
    Light rum spends less time (if any) in a barrel. It is usually filtered, diluted, then immediately bottled. It has a subtler flavor than dark rum and is often used in cocktails.
  • Dark rum
    Aged in charred wooden barrels to produce a very strong and sweet spirit. Dark rums come in grades of black, brown, and red.
  • Spiced rum
    This is dark rum which has spices added to it during production. The most common spices added to rum include cinnamon, pepper, and aniseed.
  • Gold rum
    Rum that has been aged in white oak barrels.
  • Premium rum
    A rum that is made with very high quality ingredients and carefully aged.

Differences between rum and whiskey

The mash bill

Whiskey is made from a fermented mash containing grains. The types of grains used will vary based upon the type of whiskey and the region where it is being produced.

Rum, on the other hand, is made from a fermented mash containing sugarcane byproducts like molasses or sugarcane juices. This is the main reason why the two spirits have such different flavors.

They taste and smell different

There are many different rum and whiskey products offering a wide range of flavors and aromas. However, rum usually tends to be the sweeter of the two spirits, with a rich and spicy flavor.

Whiskey tends to have more aromatics and retains oak flavors from its time in the barrel. Bourbon and run share the most similarities in terms of flavor profile, but most drinkers still find them quite distinct from another.

Different origins

Whisky was first produced in Scotland in the late 15th Century. For many years afterward, it was primarily a product made in Scotland and Ireland.

Whiskey eventually made its way to the United States and by the late 18th century, rye whiskey was being made in large quantities in the U.S. Several new forms of whiskey were also developed over the years, including bourbon whiskey, corn whiskey, and sour mash bourbon whiskey.

Historians believe that rum was first distilled on sugarcane plantations in the Caribbean in the 17th century. It was discovered when plantation slaves realized that molasses, a by-product of sugar production, could be fermented into alcohol. Rum was also being produced in Brazil in the early part of the 17th century.

How Whiskey And Rum Are Made

Whiskey and rum are both distilled alcoholic spirits, so they are produced using a similar process:

Ingredient preparation

All spirits require a source of starchy sugars. These sugars are used to create a fermented solution that is later distilled to make the spirit. In the case of whiskey, the starchy sugars are obtained from some form of grain. The grain must be cleaned and milled before it can be used in the whiskey production process.

For rum, the source of starchy sugars is a sugar cane byproduct, like molasses or sugar cane juices. These ingredients need to be processed or purchased by the distillery. Many rum distilleries are located close to a sugar cane mill, which makes it easier to obtain high quality ingredients.

Sugar cane growing

Sugar cane is a key ingredient in rum

Sugar extraction

The next step involves extracting sugars from the grains or cane sugar byproducts being used. If whiskey is being produced, hot water is added and the solution is gently agitated to produce a mash. Eventually, the starchy sugars in the grains will break down and be released into the water.

It is much easier to extract sugars from rum ingredients as molasses and sugar cane by-products release their sugar content very easily. Distillers simply add some hot water and stir the solution to release sugar molecules.

Fermentation

Once the sugars have been extracted, the solution is allowed to cool slightly before yeast is added. The yeast will begin to break down the sugars, turning them into alcohol and small quantities of a compound called “congeners”, which contribute to the spirit’s flavor. This solution, called the “wash”, is usually left to ferment for several days.

Distillation

The distillation process involves heating the wash so the alcohol it contains (which boils at 78C) vaporizes, while the water it contains (which boils at 100C) remains a liquid. The alcohol is separated and cooled by a condenser so it becomes liquid once more.

The alcohol collected after the first distillation is about 20% ABV. It is funneled off to a separate still to be distilled once more. This produces a spirit that is about 70% to 80% ABV. Some producers will distill their product a third time to create a smoother spirit.

Maturation

Finally, the spirit is placed into a wooden barrel to mature. The type of wood used to make the barrels has an impact on the way it matures and certain products require a specific wood to achieve the desired flavor. Rum often uses white oak while whiskey manufacturers usually use charred oak. In some cases, spirits will be aged in casks that were previously used to hold sherry or wine.

While sitting in the barrel, a complex chemical interaction occurs. The alcohol content of the spirit will reduce, harsher flavors will mellow, and the timber will impart some flavor into the spirit.

How long the spirit is aged will depend on several factors including the type of spirit being produced and the climate where the temperature where the cask is located.

It’s common for whiskey to be aged anywhere from 3 years to 21 years. Rum tends to be aged less, often because the distilleries are located in warm environments like the Caribbean.

Bottling

After spirit, the whiskey is placed in a bottle and is ready to be consumed.