Zeiss Reticle 4 is classic German # 4 reticle. It is combination of thin crosshair and three posts: one at the bottom and two from both sides. This reticle is popular in Europe. Reticle # 4 allows quick aiming due to its heavy posts so it is good in dynamic situations. Thin crosshair allows to aim precisely if you have a time.
Heavy posts of Zeiss #4 Reticle are visible at the dusk or early morning even against of the dark background. However center crosshair fades away at low-light condition and you should aim between heavy posts that is not so precise.
Zeiss Reticle # 6 is modernization of # 4 reticle. It has twice wider opening between heavy posts. Thus heavy posts covers less space allowing to observe wider picture. Reticle 6 is good for fast moving targets. As #4 reticle Zeiss #6 allows fast target acquisition and precise aiming at the daylight condition when you have a time.