There are two types of data roles in Tableau – discrete and continuous dimension.

Discrete data roles are values that are counted as distinct and separate and can only take individual values within a range. Examples: number of threads in a sheet, customer name or row ID or State.

Discrete values are shown as blue pills on the shelves and blue icons in the data window.

Continuous data roles are used to measure continuous data and can take on any value within a finite or infinite interval. Examples: unit price, time and profit or order quantity.

Continuous variables behave in a similar way in that they can take on any value. Continuous values are shown as green pills.