@@IDENTITY vs SCOPE_IDENTITY() vs IDENT_CURRENT – Retrieve Last Inserted Identity of Record

@@IDENTITY	SCOPE_IDENTITY	IDENT_CURRENT	IDENT_SEED	IDENT_INCR
Any table Current session Any scopes.	Any table Current session Current scope.	Specific table Any session Any scope.	Returns the original seed value If we re-seed using DBCC CHECKIDENT won't change the value.	Returns the increment value specified during the creation of an identity column in a table or view that has an identity column.
Table or View	Table or View	Table or View
If user truncates or drop the table also, it will return the last identity value generated in the current session	If user truncates or drop the table also, it will return the last identity value generated in the current session	If user truncated the table it will return the Ident_Seed value. It return null when user drop the table.

A scope is a module: a stored procedure, trigger, function, or batch.
Each query window in Query Analyzer is a session.

How to get all the session running in the server?
EXEC sp_who 'test';

How to check the current session

SELECT @@SPID       SessionID,
       USER_NAME()  AS [User_Name] ,
       SUSER_NAME() AS [Login identification name of the user.],
       CURRENT_USER AS [Name of the current user] ,
       SYSTEM_USER  AS [System_user],
       SESSION_USER AS [Session_user],
       USER         AS [User]

IDENT_SEED

1. DBCC CHECKIDENT ('dbo.IdentityTest', RESEED, 10)
2. Returns the original seed value, if we re-seed using DBCC CHECKIDENT.

3. IDENT_SEED will return the seed value created for the Idetntiy column( when table creation or Alteration).

   It won't changed by DBCC CHECKIDENT ('dbo.IdentityTest', RESEED, 10)

References
RESED Identity Column
SQLAuthority