Step 1 :The question is asking to simplify the expression \( \log _{b} 6-\log _{b} 6 \).
Step 2 :From the properties of logarithms, we know that the difference of two logarithms with the same base is equivalent to the logarithm of the quotient of the numbers.
Step 3 :Therefore, we can simplify the expression as \( \log _{b} \frac{6}{6} \).
Step 4 :Since any number divided by itself is 1, the expression simplifies to \( \log _{b} 1 \).
Step 5 :Finally, the logarithm of any base to the power of 1 is always 0.
Step 6 :So, the simplified form of the expression \( \log _{b} 6-\log _{b} 6 \) is \( \boxed{0} \).