Breast

Portion breast is used in restaurants to help ensure costs per plate of food are kept consistent. Portion breast are all cut to a customer specified weight per piece.
Random breast means that all pieces of chicken will fall within a certain range of varying sizes.
Whole breast is where the breast bone is still attached. Bone-in chicken breast is best suited for longer cooking methods, such as roasting, braising, and barbecuing. The bones may also be used for chicken stock.

3-8 oz boneless skinless portion breast

6-8 oz boneless skin on portion breast

Random boneless skinless breast

Whole breast