Bags are sections of material or fabrics that are utilized to carry objects. Bags can be any variety of sizes, colors and shapes.
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.
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.