Highlighters and color are used to group or classify the field values using color.
Let me just point out points -
1. A color shelf can show multiple views (Colors >=0) whereas highlighter can only show or provide dual view (colors =2, highlight and non-highlighted).
2. You use a highlighter to compare or focus on specific data whereas color shelf focuses on all fields equally.
3. Colors used in color shelf can be edited whereas highlighter cannot be edited.
To use Color shelf, drag and drop a field in color shelf.
To use highlighter, Click on Analysis Tab, and go to highlighter and then select the field to use as a highlighter.
Color shelf -
Hope this helps you.