Strips are cut to panel length and are quick to fit: thread them in, done, no measuring. In return, a butt joint appears at every post, which is visible in backlight.
Rolls run continuously across several panels, which makes for a calmer appearance. In exchange, you have to trim them yourself at the end of each run and will sensibly want an unwinder. For straight, long fences the roll is the better choice; for angular plots with many short panels, the strip is.