Step 1: Understand the given condition.
We are given that \( 0<x<y<1 \), and we are asked to compare \( 1 - y \) and \( y - x \).
Step 2: Try two approaches.
Approach 1: Number line.
On a number line, \( 1 - y \) is the distance between \( y \) and 1, and \( y - x \) is the distance between \( y \) and \( x \). Depending on the values of \( x \) and \( y \), these two distances may or may not be equal.
Approach 2: Plug values for \( x \) and \( y \).
For example, if \( x = 0.4 \) and \( y = 0.5 \), then:
\[
1 - y = 1 - 0.5 = 0.5, \quad y - x = 0.5 - 0.4 = 0.1
\]
In this case, \( 1 - y \) is greater than \( y - x \). However, if \( x = 0.1 \) and \( y = 0.9 \), then:
\[
1 - y = 1 - 0.9 = 0.1, \quad y - x = 0.9 - 0.1 = 0.8
\]
Here, \( y - x \) is greater.
Step 3: Conclusion.
Since the relationship depends on the specific values of \( x \) and \( y \), the correct answer is that the relationship cannot be determined from the information given.
Final Answer:
\[
\boxed{\text{The correct answer is (4) The relationship cannot be determined from the information given.}}
\]