Let the two numbers be \( x \) and \( y \).
From the given conditions:
\[
x + y = 42 \quad \text{and} \quad xy = 437
\]
Step 1: Using the identity for the difference of squares:
\[
(x - y)^2 = (x + y)^2 - 4xy
\]
Step 2: Substitute the known values:
\[
(x - y)^2 = 42^2 - 4 \times 437
\]
\[
(x - y)^2 = 1764 - 1748 = 16
\]
Step 3: Taking the square root on both sides:
\[
x - y = \sqrt{16} = 4
\]
Thus, the absolute difference between the two numbers is \( \boxed{4} \).