function valid for when two of the arguments are different?

Questions
1

Hi People.
I have a data set of numbers which can be described as follows :

{{{a,b,c,d},{g,h,k,l}},{{a,b,c,d},{g,h,k,l}},{{a,b,c,d},{g,h,k,l}},{{a,b,c,d},{g,h,k,l}},{{a,b,c,d},{g,h,k,l}}....}

And I’m trying to use the function:

f3[{{a_, b_, c_, d_}, {g_, h_, k_, l_}}] := ( [(l - d)] + 0.01)/((Max[h, d]) - (Min[k, d]) + 0.01)

The thing is that I like the function to be used only in the case when l and d are not equal.
I tried to use /; but the messages the mathematica issued were not clear enough for me .

2 
f3[{{ a_, b_, c_, d_},{g_, h_, k_, l_ }} /; Unequal[l,d] := (l - d + 0.01)/( Max[h,d]) - Min[k,d] + 0.01 )
3

Thank you for clue