To find out how much more Maren's kitten weighs than Lynn's kitten, you need to subtract Lynn's kitten's weight from Maren's kitten's weight:
\[ 86.23 , \text{ounces} - 67.74 , \text{ounces} = 18.49 , \text{ounces} \]
Thus, Maren's kitten weighs 18.49 ounces more than Lynn's kitten.