Explanation
B: Column distribution: This feature provides a set of visuals underneath the names of the columns that showcase the frequency and distribution of the values in each of the columns. The data in these visualizations is sorted in descending order from the value with the highest frequency.
By hovering over the distribution data in any of the columns, you get information about the overall data in the column (with distinct count and unique values).
A: Column profile: This feature provides a more in-depth look at the data in a column [compared to column distribution]. Apart from the column distribution chart, it contains a column statistics chart.
Reference:
https://docs.microsoft.com/en-us/power-query/data-profiling-tools