please answer in detail

2.6. Question 6 What is the difference between the codes below? What is the result after compiling and running? #include void fun(int x) { x = 30; } #include void fun(int *ptr) { *ptr = 30; } int main() { int y = 20; fun(y); printf("%d", y); int main() { int y = 20; fun(&y); printf("%d", y); return 0; return 0; } }