Global Temp Variable:
Global temp tables name starts with double hash (##) in sql server. Once this table is created in database, it is like a permanent table in tempdb->temporary tables. It is always ready for all users and not deleted until the total connection is withdrawn.
CREATE TABLE ##StudentTemp
Local Temp Variable:
Local temp tables are only available at current connection time in sql server database. It is automatically deleted when user disconnects from instances. It is started with hash (#) sign.
CREATE TABLE #localTemp