Simply put, Ren meridian is the midline in front of the human body, and Du meridian is the midline behind the human body. More specifically:

Renmai-starting from cells and ending in mandible, there are 24 acupoints related to Yuan and Qi-hai. (Figure 1)

Du Meridian —— It starts from the uterus in the lower abdomen, goes down to the perineum, goes back to the Changqiang point in the sacrococcygeal region, goes up along the back of the human body, passes through the nape back to Fengfu point, enters the brain, goes to Baihui point on the top of the head along the midline of the head, goes down from the forehead to Suxiu point at the tip of the nose, and passes through the middle of the human body to the gum point at the middle of the upper teeth. (Figure 2)