@AndrésC64 in my country, if you had a slice of chicken-breast like this format, it would be more common to put that between simple slices of bread. But it's also something people consider funny due to its simplicity. So the meal on the picture above is made incorrectly :D For the record I ate such a sandwich yesterday, tasted great!
If the meat has been put through a meat grinder, then it's a burger. If the meat is not ground, it's a sandwich. The bun shape and type of animal is irrelevant. The meat must be ground for it to be a burger. That's burger law.
A burger IS a sandwich, technically, as it's quite literally meat, veggies and sauces "sandwiched" between two pieces of bread, so it'd still be a sandwich no matter what you call it.
s 
