Difference between APP_NAME() and PROGRAM_NAME()

Hi,

We are passing Application Name dynamically from the connection string (.net) and using it in SQL 2008 trigger using PROGRAM_NAME() from sys.dm_exec_sessions. Most of the time we get the desired result but sometimes it returns ".Net SqlClient Data Provider".

Please suggest is there any issue in using sys.dm_exec_sessions. We are using following query to get application name in trigger.

"select top 1 program_name from sys.dm_exec_sessions"

Should we use APP_NAME instead?

Please help.