We know $0 < x < y < 1$. Let's test specific values to see if the relationship is fixed.

Example 1: $x = 0.1,\ y = 0.2$.
Quantity A: $1 - 0.2 = 0.8$. Quantity B: $0.2 - 0.1 = 0.1$. A > B.

Example 2: $x = 0.1,\ y = 0.9$.
Quantity A: $1 - 0.9 = 0.1$. Quantity B: $0.9 - 0.1 = 0.8$. B > A.

Since the relationship changes depending on the values of $x$ and $y$, it cannot be determined from the information given.