Virtual are attributes which are based on a micro flow. These attributes are not stored in the database but every time the objects is retrieved or changed the virtual attributes are recalculated again.
Information about attributes can be found here.
Explanation how to deal with calculated data can be found here.
There are multiple drawbacks for virtual attributes, I recommend to use them as little as possible!!
These are attributes that calculate their value by use of an micro flow that you can design yourself. They are not stored in the database, but are recalculated everytime you retrieve the value. Please note that you can't use Xpath queries on these attributes and therefore you can't search/sort on their values in a data grid.
These attributes can be used to display values that can change at any time.