Both tend to be flexible and cyclic. In both instances, there is a desire to base planned changes in the situation on understanding, and to derive that understanding from evidence. Because of these and other similarities, less formal approaches to action research may be very similar to some forms of practice. However, most forms of action research are more deliberate in their pursuit of understanding. Most importantly, frequent critical reflection is a formal and central part of most action research.
Most practice is much less reflective than action research.
Most practice, if it does use reflection, is neither as deliberate nor as critical in its use. There are other processes which do use regular and systematic critical reflection. Action learning and experiential learning provide two example. These and action research have much in common, and shade into one another at the boundaries. In the sense of explanations given in terms of causal relationships between variables, generally not.