European-style unsweetened cocoa powder vs Hershey's Cocoa?

What is the difference between Hershey's Cocoa powder and European-style unsweetened cocoa powder?

I take it one is stronger than the other? I am trying to make a diabetic dessert and it called for the European-style. If I cannot find it, will the regular cocoa work?

This is the recipe I thought I would make since I have family members who are diabetic:

Brownie Sunday Pie

vegetable cooking spray

2/3 cup sugar

1/4 cup reduced-calorie margarine, melted

1 large egg

2 tablespoons Butter Buds Sprinkles

1 teaspoon vanilla extract

1/2 cup all-purpose flour

1/3 cup European-style unsweetened cocoa powder

1/2 teaspoon baking powder

1/8 teaspoon salt

1/2 cup reduced-calories frozen whipped topping, thawed

1/2 cup sliced bananas

2 tablespoons chopped walnuts

1 1/2 cups nonfat vanilla frozen yogurt (optional)

Thank you in advance for your kind answers.