The rules of the alcohols drinks
European regulations impose a minimum thresholds for the degree of alcohol included by spirits.
EC n° 110/2008 (1)
45% for pastis de Marseille
40% for whiskey and other pastis
37.5% for rum, gin, brandy, vodka, ouzo, grappa
36% for brandy
35% for anise
25% for spirit drinks based on fruit
The legal age in Europe is 18 to consume alcohol. (Some local exceptions may apply)
In the USA, regulation of alcoholic beverages is not the same, the legal age is 21 years throughout the country.
And on the Vol. alcohol, the rates are different from the European Union.
40% for spirits (Gin, Vodka, Whisky, Brandy, Rum ...) (2)
Of course, some brands adapt their product to the regulations but then it is no longer exactly the same product.
The alcohol content is adjusted to a minimum of local regulations, to reduce facial price. So some disrespectful trademarks of their recipe, vary the concentration of alcohol or as you are. Look in the duty-free, it's even more amazing alcohol levels soar for some brands. Respect for the original recipe is gone.
The higher the alcohol level is important addition, more flavors and botanical from the distillation go out and better your cocktail.
Diplôme Dry Gin is always and all around the world at 44% vol.