Analysis :: Difference Between A Set Of Tuples And A Set Inside A Tuple

I wanted to understand the basic difference between the following two MDX queries which give two different outputs - 

1. Set of Tuples -

Query-
SELECT
[Measures].[Internet Order Count] ON 0
FROM
[ADVENTURE WORKS]
WHERE

[code]....

2. Tuples in a Set -

Query-
SELECT
[Measures].[Internet Order Count] ON 0
FROM
[ADVENTURE WORKS]

[code]...

From the output i am getting on the MDX, i understand that the analogy is not correct. But I am not able to understand the difference between the same.