Concept: The question tests on the ability to solve a question on Factors and divisibility
The divisibility test of 4 is that the last 2 digits has to be divisible by 4. So yz is divisible by 4.
The divisibility test of 8 is that the last 3 digits has to be divisible by 8. So xyz is not divisible by 8.
The least possible value of xyz would be 004. The maximum possible value would be 996.
The difference = 996 - 004 = 992