My first serger a Babylock 3/2 thread is well over 20 years old. Sergers were fairly new to the home market and the dealer that sold through my shop carried New Home machines and Babylock sergers. 3/2 thread means it will serge with three threads or two threads. This little machine created the nicest of all two thread rolled hems. A real work horse of a machine and yes, it still does work.
Next to join my sewing room is the White. The White is a 4/3 thread, meaning you can serge with four threads two being needle threads or you can remove one needle and serge with three stitches, most often used to finish the seams. I purchased the White to see if I really did need a 4 thread serger. I was very happy to be able to serge wider seams and often made garments using just the serger. So that of coarse lead to an upgrade.
You might say “you have come along way baby” My current serger a 4/3/2 thread. Just a push of a button has you serging away. A big change from the first serger. A very quiet machine and also does a wonder rolled edge. There are several different feet available for this machine but I have not collected them yet. I am anxious to try to learn how to do different types of serging.