Correct Answer: 50890

To find the difference between the lowest and the highest number in Step II, we first need to decode the rules of the number arrangement machine by analyzing the illustration.

Rule for Step I:
For each 5-digit number, the digits are transformed as follows:
1. Multiply the 1st and 2nd digits to get the first part.
2. Subtract 1 from the 3rd (middle) digit to get the second part.
3. Multiply the 4th and 5th digits to get the third part.
4. Concatenate the three parts together to form a new number.

Let's apply this Step I rule to each number in the given input:

For 28465:
First part: $2\; *\; 8\; =\; 16$
Second part: $4\; -\; 1\; =\; 3$
Third part: $6\; *\; 5\; =\; 30$
Concatenated value: 16330

For 79784:
First part: $7\; *\; 9\; =\; 63$
Second part: $7\; -\; 1\; =\; 6$
Third part: $8\; *\; 4\; =\; 32$
Concatenated value: 63632

For 63452:
First part: $6\; *\; 3\; =\; 18$
Second part: $4\; -\; 1\; =\; 3$
Third part: $5\; *\; 2\; =\; 10$
Concatenated value: 18310

For 34867:
First part: $3\; *\; 4\; =\; 12$
Second part: $8\; -\; 1\; =\; 7$
Third part: $6\; *\; 7\; =\; 42$
Concatenated value: 12742

For 93275:
First part: $9\; *\; 3\; =\; 27$
Second part: $2\; -\; 1\; =\; 1$
Third part: $7\; *\; 5\; =\; 35$
Concatenated value: 27135

Thus, the numbers in Step I are: 16330, 63632, 18310, 12742, 27135.

Rule for Step II:
Arrange the numbers obtained in Step I in descending order.

Sorting the Step I numbers in descending order: 63632 > 27135 > 18310 > 16330 > 12742.

Thus, the numbers in Step II are: 63632, 27135, 18310, 16330, 12742.

From Step II, we can identify:
Highest number = 63632
Lowest number = 12742

Now, calculate the difference between the highest and lowest numbers:

$Difference\; =\; 63632\; -\; 12742\; =\; 50890$