The two electrons in K sub-shell will differ in

Two electrons in K-shell will differ in spin quantum number.
They will have same values for the principal quantum number,  azimuthal quantum number, and magnetic quantum number.

For first electron, n=1,l=0,m=0,s=$+\frac{1}{2}$
For second electron, n=1,l=0,m=0,s=$-\frac{1}{2}$