Carry on refers to any type of luggage or bag designed to easily and efficiently carry personal belongings when traveling. Some carry on bags are designed with rolling wheels underneath for easy transport while other are small bags that feature handles or shoulder straps. Typically, carry on bags feature extra pockets and compartments that make organizing passports and ID's simple and convenient.
Suitcases are separate pieces of luggage that are used to contain items for use in travel. Suitcases often have wheels on the bottom of the bag to ease in the movement of the piece.