What is difference in meaning?

[Larry9999]

Sorry, this is my first post and I don't know what to do to type Korean with my computer, so I'll have to use romanization.
What is the difference and when do you use two words which seem to mean the same?
The words are "musun" and "awtten". I learned both of these words to mean "what kind of..., what type of ..., etc". Is there a difference in the meaning or which one is used with certain words, such as when you ask, : What kind of book...?, or What kind of relationship do you have with...?, or What kind of machine is that?, etc.
Thank you.

[manyakumi]

They are almost the same.

무슨 책이에요? : What book is it? (What is the book for?)
어떤 책이에요? : What(Which) type of book is it?

What kind of relationship do you have with?
무슨 사이예요? and 어떤 사이예요?
Exactly same.