区别就是两者都是合成词+water的短语,具体的不同如下

spring water中文意思是泉水

It is a kind of hot spring water, which contains the mineral base, to restore and transform it into weak alkaline water.

pure water中文意思是[化学] 纯水,净水纯净水

The bottle is sealed, and the label says "pure water".