In North America, a chicken sandwich is a sandwich which typically consists of a boneless, skinless breast of chicken served between slices of bread, on a bun, or on a roll.
A sandwich is a food item consisting of one or more types of food, such as vegetables, sliced cheese or meat, placed on or between slices of bread, or more generally any dish wherein two or more pieces of bread serve as a container or wrapper for some other food.
Bread is a staple food prepared from a dough of flour and water, usually by baking.
SPICY FRIED CHICKEN SANDWICHES - How to make Spicy Fried Chicken Recipe by Foods101withDeronda
Variations of what North Americans consider a "Chicken Sandwich" include the chicken burger or chicken on a bun, hot chicken, and chicken salad sandwich.
Chicken and Mayo Sandwich by Sanjeev Kapoor Khazana
Countries outside of North America generally consider a chicken sandwich to only consist of flat bread, whereas a chicken burger is defined by the use of bread buns with chicken as part of its content.