Backpacks are bags that possess two shoulder straps which allow the wearer to carry the bag on their back. Backpacks are often associated as a student's must have school accessory for carrying books, etc from class to class.
About Bags:
Bags are sections of material or fabrics that are utilized to carry objects. Bags can be any variety of sizes, colors and shapes.
About Mesh:
Mesh refers to a material that is netted and is punctured with minor openings. Mesh is typically found on athletic and casual footwear to provide comfort and breathability.