Pareto Chart is a graphical tool to help identify 'Vital Few from Trivial Many'. It is based on Pareto's principle which states that 80% of the defects are due to 20% of the causes. It is a bar chart depicting in descending order the frequency of the different defect categories. The bar chart is superimposed with a line graph which shows the cumulative percentage on a secondary y-axis. As per the principle, approximately 80% of my cumulative defects will be caused by 20% of the defect categories (starting with the categories from far left).
Weighted Pareto is a modified Pareto which helps in assigning weightages to different defect categories thereby overcoming the limitation of a normal Pareto where all defects are considered to be of same severity. The most common parameter used for weightage is the cost of a defect but other parameters can also be used. Once the weightage is decided, the bar graph is plotted with the product of weightage and frequency (instead of frequency alone) in the decreasing order. Rest everything remains similar to a normal Pareto Chart.
An application oriented question on the topic along with responses can be seen below. The best answer was provided by Vastupal Vashisth on 15th September 2018.