Achart is two separate charts put together as one.

Combo chart is useful to put two separate charts together as one.

Explanation:

Under the recommended chart in the excel the ‘Combo’ option is used to put two different separate charts into one. First, select two types of sets of data you wish to visualize in a chart. Under the Insert tab in the application ‘Recommended charts’ to be chosen. At last ‘Combo’ chart option will be shown in the list of chart types. Choose the ‘combo’ option and follow the procedures to make a chart to put two separate charts into one.