Why is there a little bit among patents?

There is no difference. The last digit is the check digit, and the range of 0- 10, 10 is represented by X. The ID number also has similar digits, and its value is related to all the previous values. If any of the previous values is wrong, the check bit will change, because the application number can be checked for authenticity, especially in the input process, the corresponding software can check whether it is correct.