When I got my first set of studio lights, I was met with a huge variety of different accessories I could get. I wanted a diffuser in order to create that soft light while photographing products. The two choices I had were between a Softbox or an Octabox. So what are the differences between them?
A Softbox is a generic term for something that softens light. It is there to reduce the harshness of the shadows within your image. An Octabox will cover the same functions as a basic Softobox. We shouldn't be looking at the two products trying to compare what they do but rather what purpose they would serve you and your work. Are you a product photographer? Or perhaps you focus more on Fashion and Portraits?
The most obvious difference between the two is the shape. An Octabox, as the name suggests has eight different corners creating an octagon, whereas a Softbox typically comes as a rectangle or square. If you predominantly work with people and take portraits, then you would probably be better off getting an Octabox. This is entirely down to the shape and the reflection it would create in the eyes of your subject. A circular light reflection in the eyes would look far more natural and appealing than a rectangular one. Think of an Octabox as a specialist type of Softbox.
Finally, consider the size and where you will be predominantly shooting. If you're going to be in a decent sized studio most of the time then this won't matter too much. However, if you're on the go a lot then you want to consider how long it takes to set up, take down and how portable they are. Whichever one you decide to go for, keep in mind the purpose of why you need it.