What is the key difference between a Dry Manhattan and a Regular Manhattan?

The key difference between a Dry Manhattan and a Regular Manhattan lies in the amount and type of vermouth used in the cocktail. A Regular Manhattan typically uses sweet vermouth, while a Dry Manhattan substitutes sweet vermouth with dry vermouth, which significantly alters the flavor profile of the drink. The term "dry" emphasizes that less sweet flavor is present due to the use of dry vermouth, providing a crisper and less sugary taste compared to its regular counterpart. This change in the vermouth choice is essential for bartenders and enthusiasts to understand, as it directly affects not only the flavor but also the overall character of the cocktail.