The day pack is a relatively light bag that is mostly used for day trips and simple overnight trips. Daypacks usually have a capacity between 15 and 35 litres. As well as having simple designs, daypacks tend to offer a minimal amount of features and are mainly designed for formal or casual settings, like work, hiking, and overnight trips. As opposed to a purse, a backpack is a bag with shoulder straps. The difference between a daypack and a backpack is that a daypack is smaller, whereas a backpack can be bigger or smaller. Backpacks come in many forms, including hiking and backpacking bags. More information about the 31 different types of backpacks can be found in my detailed review.