"Frappe: In Boston and eastern Massachusetts, this is what the rest of the country calls a "milkshake," which is a drink traditionally made with ice cream, milk, and syrup, and beaten on a milkshake mixing machine.

Milkshake: 1. In most of the country, this is a drink traditionally made with ice cream, milk, and syrup, and beaten on a milkshake mixing machine (see also "frappe"). 2. In Boston and eastern Massachusetts, it is a drink made with milk and syrup (no ice cream), and beaten on a milkshake mixing machine. It is light and frothy, not creamy and thick like the drink described in definition #1.

Source: Herrell's Dictionary: Ice Cream from A to Z! "

Bitt - sorry!

-Zeke

further reference: http://www.thefreedictionary.com/frappe