I divide 'em up this way...
Hand foods are sandwiches.
Then you got open-faced,
Closed over, hot and cold.
Adding to the controversy, I consider Pizza a hot (or cold) open-faced sandwich.
A chicken pot pie is not a sandwich
A schnitzel is not a sandwich
Beef wellington is not a sandwich.
But, in my view samosas, pitas, gyros, tacos, vietnamese salad rolls, wraps, spring rolls, subs, hot dogs & burgers: all sandwiches.
Cannot decide on the corn dog though... It's on a damn stick!!! WTF?
I have put way too much thought into this, and now I am just plain hungry.