I ask myself that question all the time. Well? Both, I guess.
I start with a beginning and an end and then fill in the rest. It’s a little more than that. A series of events are thought of to get to that end, but not every detail is plotted out. That makes me more a Pantser with a mimimalist outline than a Plotter. Then, on the other hand, there are times when everything is plotted before writing begins. What does that make me, then? A Hybrid?
Whatever you may be, it is a personal preference based on your personality type. The following is a list of article dealing with that subject, and they can likely explain the differences better than I.
Have an enjoyable read.