Such a huge difference!
Once you finish spinning up your singles, it's time to decide how to ply. For 2 plies or 4 or more, you only have one option. But at the magic 3-ply point, you have two choices: regular plying, or chain plying (also called Navajo ply, because it is the traditional technique used by Navajo spinners). Each technique has its advantages and drawbacks.