Just as wine; tasting whiskey is best explored by direct judgment and evaluation which is how you get the appreciation of flavor distinctions and differences.

But unlike in wine tastings, the nose or bouquet is not one of the overriding aspects in drinking whiskey.

…Usually, the ultimate impression of the nose is typically gone after the long savory finish.

There are 5 main areas/regions for whiskey to compare…I have included some key background
info:

 

1.       Scottish whiskey (Scotch; in Scotland it is spelled whisky…As a general rule, American-produced and Irish varieties spell the spirit, “whiskey,” while Scotland, Canada, and Japan refer to it as “whisky.”)

Also, note that a single-malt whiskey is the product of a single barrel and does not mean that it is of a higher quality.

The “single” part only means that the whiskey is the product of one distillery, not the kind of grains or number of grains that go into the whiskey.

2.       Kentucky whiskey (Bourbon;  is defined as any straight whiskey made from at least 51 percent corn that has been aged in new charred oak barrels in the United States.

Also note that Scotch whisky ‘can’ be aged in old oak barrels, so a lot of the barrels are sent from the United States to Scotland after they have been used to age bourbon.

3.       Canadian whiskey

The rule for Canadian Whiskey is that It must be fermented, distilled and aged in Canada. That’s it. Like bourbon it is usually made from several different grains. But in Canada each grain is usually fermented, distilled and aged separately. They are only combined together at the very end. Which changes things a whole lot for the Whiskey.

4.       Tennessee whiskey

 
Tennessee whiskey is straight bourbon whiskey produced in Tennessee. Arguably, Tennessee says it is not Bourbon! It is whiskey created by distilling a fermented cereal grain mash to create a spirit not exceeding 80% alcohol content by volume aging the spirit for at least two years at a concentration not exceeding 62.5% at the start of the aging process. The whiskey is soaked in charcoal chips before going into the casks for aging.

 
5.       Irish whiskey

Most Irish pot still whiskey is distilled thrice (three times), while most, but not all of the Scotch whisky is distilled twice. Peat is hardly ever used in the malting process, so that Irish whiskey has a smoother finish as opposed to the smoky, earthy nuances apparent in some Scotches

 
Furthermore, Here are some flavor profiles and some overall impressions:

 1. Scotch is the prototypical explosion of malt, peat and scorched soil. Single-malt scotch means that the barley used stems from a single distillery, no blending. The flavor is relatively sharp and earthy.

 2. Bourbon is corn-driven and usually blended, letting a more creamy, round and gentler flavor than the stately but stoic Scotch counterpart.

 3. Canadian whiskey can be even more softer and sweeter than the higher-end Bourbons. A caramel-like impression is a characteristic. It sometimes feels more delicate in comparison to American whiskey.

 4. Tennessee is recognized for their sugar maple charcoal filtering process. Highly similar to Bourbon in general. It is similar to Scotch in that it is usually aged in new charred oak barrels, for at least 2 years

 5. Ireland doesn’t malt their barley, and that absence becomes very clear on the palate. Scotch is smokey and peaty. Irish whiskey is a lot more perfumed and round on the palate.