[quote=@Strange Rodent]
So how do they differ from sandwiches in your definition enough to call them different things?
[/quote]


Because different foods have different names. Wolves and dogs are both canines but you don't typically keep wolves as a pet. Ravioli is a dumpling, not a sandwich. Pie isn't a sandwich. If someone asks you for a sandwich and you bring them ravioli they're going to look at you like an idiot. If you want to get super technical, pie isn't sliced nor is ravioli and moreover pie doesn't have the leavening agent of yeast that is vital to the bread component of a traditional sandwich. 

This is one step away from being "An ice cream cone is a sandwich!"