We are asked to compare the probability that the four numbers rolled on a die are distinct and in ascending order with the given value 518518.
Step 1: Calculate the probability.
When rolling a die four times, the total number of possible outcomes is:
\[
6^4 = 1296
\]
Now, for the numbers to be distinct and in ascending order, we need to choose 4 distinct numbers from the 6 available options and arrange them in one specific way (ascending order). The number of ways to select 4 distinct numbers from 6 is:
\[
\binom{6}{4} = \frac{6 \times 5}{2 \times 1} = 15
\]
Since the numbers must be in ascending order, there is only 1 way to arrange each selection. Therefore, the probability is:
\[
P(\text{distinct and in ascending order}) = \frac{15}{1296} = \frac{5}{432}
\]
Step 2: Compare with Quantity B.
Given that Quantity B is 518518, which is much greater than \( \frac{5}{432} \), we can conclude that Quantity A is smaller than Quantity B.
Final Answer:
\[
\boxed{\text{Quantity B is greater.}}
\]