Duffels are rectangular bags with handles and typically a shoulder strap. Duffels are often made of nylon or leather and used for short trips or commonly used as a Gym Bag.
About Luggage:
Luggage is any number of bags, cases and containers which hold a traveller's articles during transit. Types of luggage include Suitcases, Duffel Bags, and Tote Bags. Today many types of luggage have wheels as an added convenience.
About Zipper:
A zipper, sometimes called a 'slide fastener' is a device consisting of two toothed tracks or spiral metal or plastic coils, each bordering one of two edges to be joined, and a piece that either interlocks or separates them when pulled.