In Mandarin, how do you distinguish between "终点" (endpoint) and "中点" (midpoint)?

终点 (zhong dian) means finishing line. for example: he reached the finishing line within 10 seconds. 他以十秒钟内到达终点

中点 (zhong dian), like you said, means midpoint. for example: usually, there's a refreshment given to the participants at the midpoint in a marathon race. 跑者往往会在马拉松比赛的中点给于饮料喝... to tell you the truth, we rarely used the word "中点" in our sentence. normally, we replace it with this word "途中" (tu zhong), which can be referred as midpoint as well. so the proper translation to the given example would be "跑者往往会在马拉松比赛途中给于饮料喝"

The short answer is you cannot. This is why Chinese is a very poor language for public address, or even poetry reading, if you do not have the written text to glance at at the same time. It is the curse of having so many words that sounds exactly the same.

We Chinese handle this by trying to inquire further, so that we can distinguish the context in the 终点”而非“中点”. Give you an example, when you see Chinese being introduced to each other, they will say .. This is Mr. Zhang. Many times, Mr. Zhang will say voluntarily to the guy --- '立早- 章' This is to save the other guy from mistaking it as the 張, 弓長 張. Now do you understand the full effect of our curse ?

That's just like how you distinguishi between "two" and "to" in English
They're just pronounced exactly the same,right?
So it's depends on the meanin of the whole sentence