DAX compare data from different tables

I am trying to find differences between two tables carrying the same data but from different sources. I need to find differences. Can anyone please support!

Table 1:
Employee_Code
Salary_Month
Net_Salary

Table 2:
Employee_Code
Salary_Month
Net_Salary

Custom Calendar:
Date {from 1st Jan 2018 till 31st Jan 2018}
Month

Direct Relationship:
Table 1[Employee_code], Table 2[Employee_code]

Table 1[Salary_month], Calendar[Month]

Indirect Relationship:
Table 2[Salary_month], Calendar[Month]

I am trying to find the difference was in which month, unfortunately, both the below DAX does not calculate.

DAX Formula used:
Difference1 = CALCULATE(SUM('Table 1'[Net_Salary]))- CALCULATE(SUM('Table 2'[Net_Salary]))

Difference2 = CALCULATE(SUM('Table 1'[Net_Salary]))- CALCULATE(SUM('Table 2'[Net_Salary]), USERELATIONSHIP('Table2'[Salary_Month], 'Calendar'[Month])

Required output: