In Australia, shops often sell sets of 4 double pointed needles rather than sets of 5, whereas in Europe, sets of 5 are the norm. The use of both types of needle sets is very similar: You either divide your total number of stitches across 3 holding needles and knit with a fourth needle, or you divide them across 4 needles and knit with the fifth.
However, there are benefits to using a set of 5 needles which are due to the size of the angle between your holding needles. Essentially, with a 5-needle set you are knitting in a square rather than a triangle (set of 4 needles). As a result, there are wider angles between the needles when using a set of 5 compared to a set of 4 needles, and you are less likely to end up with "ladders" of looser stitches at the transition points between needles.