What is the difference between a peak area comparison and a quantitative limit for related substances?

What is the difference between a peak area comparison and a quantitative limit for related substances?

In the past, the acceptance criteria for related substances were expressed relative to the area of a reference peak of known concentration (limit test). Without providing a numerical result, the comparison of peak areas leads to a pass/fail decision. For comparative tests, the approximate content of impurity tolerated, or the sum of impurities, is indicated in brackets for information only. In most cases, the current monographs describe quantitative determinations: a calculation of the content is necessary to establish compliance with the monograph.