There are so many forms of online qualitative research, you may find yourself overwhelmed by all the choices. Fortunately, there are some key characteristics to all methods. Once you understand what these are, you can easily determine how to categorize anything new you hear about.
One big difference has to do with the dimension of time. Synchronous methodologies all happen at the same time and within a set schedule. Asynchronous approaches are scheduled as well, but over a longer period of time and participants may come and go.