When one says 咱们,he must mean him(the speaker) and his listener(s).. Mostly you can replace one word with another. But notice : when one says 我们,he can mean him and someone who he isn't in conversation with. eg.张三对李四说：咱们学校.In this case,李四 must be in the same school with张三 But张三对李四说：我们学校.Then李四might or might not be 李四's schoolmate. And 咱们 might refer to "you" or "I". eg.When encouraging someone in trouble,one says 咱们不怕，只要努力，一定能成功。Here 咱们 refers to someone in trouble. When one says咱们没上过大学，不懂那么多道理。It refers to the speaker himself. A good question ,some native Chinese can't even tell the tiny differences. Hope this helps.

This is about something called "clusivity". Both 我們 and 咱們 or simply 咱 mean "we". -我們 doesn't include the person being spoken to. -咱們 does include the person being spoken to. Take this example: If my friend and I come up to you and shout "WE‘VE JUST WON THE LOTTERY!!", you don't know if you are included in this statement. Do I mean that my friend and I have just won the lottery, or do I mean that all three of us have just won? 咱們 and 我們 can solve this problem.

Hi Crow, "咱们" and "我们" almost the same meaning, but "咱们" only be used in orality and Informal situations, "我们" is more wide range, you can use it in anywhere.

They are same but people usually use 我們.

Basically they have same meaning. But 咱们 is not so often used in southern China. And I think under formal circumstance 咱们 might not be so good as 我们.