And my Grandparents from Lowell, MASS called a milkshake a frappe.
I'm in Boston, and here they're two different things: a milkshake is just milk and syrup frothed in a blender; a frappe has ice cream blended in. As opposed to a "soda," which here is syrup and carbonated water with a scoop of ice cream added!
That reminds me of a funny story. I was in New York once, and I ordered a Frappe. The person at the counter asked me "what do you want on it?" I gave a quizzical look, and said you know, vanilla syrup and ice cream.
What I ended up with was just plain strange, it was sickly sweet and I had to throw it away. Indeed a Frappe around here is a rich milk shake. A milk shake is a frappe but more of an economy version.