isolate 侧重指完全分离、隔开，也指人或处于完全孤立的状态。
separate 指一般意义上的分开或隔开。
segregate 指把一群人或物从整体或主体中分离出来。
insulate 指隔开、分离，尤指用某种东西阻挡从里面逃出或从外面进入的东西。作技术用词时，专指用某种绝缘体隔断通路。
参考例句
1. Mary and I were segregated in the crowded square. 广场中拥挤的人群把我和玛丽挤散了。
2. Some societies still segregate men and women. 有的社会仍然将男女 隔离。
3. The controversial focus about segregate management and mixed management is risk and efficiency. 分业经营还是混业经营，一个争论的焦点就是风险和效率的问题。
英英解释
n.
1. someone who is or has been segregated
2. separate by race or religion; practice a policy of racial segregation
3. divide from the main body or mass and collect
4. separate or isolate (one thing) from another and place in a group apart from others
