Data comparison is one the main aim of many charts in Power BI. However, there is a specific data comparison chart in R "Variable Width Column Chart " which we can change the widgh of bars based on our data. I have explained the whole process of creating this chart in power bi in the below link
http://radacad.com/variable-width-column-chart-writing-r-codes-inside-power-bi-part-4
also the file and code a reavailabe for use.
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