Covers a named user that will be accessing the SQL database or application.
Preferred if each user has numerous devices.
Example: User A accesses SQL Server from their phone, workstation, and laptop at home. You will purchase 1 user CAL instead of 3 device CALs.
Covers a device that will be accessing the SQL database or application.
Preferred if you have numerous users who access the same device.
Example: You have an AM and PM warehouse team. You want both shifts to use the same device to access the SQL Database. You will need to only purchase 1 device CAL instead of 2 user CALs.
NOTE: 95% of CALs go under the "user" model as a majority of all access to a SQL database or application occurs on more devices than users.