Delete command removes the rows from a table based on the
condition that we provide with a WHERE clause. Truncate will
actually remove all the rows from a table and there will be
no data in the table after we run the truncate command.

 Delete Command require Log file updation for each row of 
deleting process. But the Truncate command not.
So, the Truncate Command is so faster than Delete Command. 

Truncate will fail if the concerned table has foreign key 
constraints while delete doesnt.

Truncate is DDL Command while Delete is DML Command

Truncate command result can be rolled back as it is not 
made an entry in the log where as Delete command result 
can't be rolled back

Delete command only delete the rows from the  table but the 
schema of the table yet remains.Whereas Truncate command 
delete the rows along with the tale's schema from the 
memory permanently.

Delete command deletes the data from the tables .. but can 
get back on issue of roll back whereas when you issue 
truncate deletes the records and oracle implicitly issues 
commit command and even when you issue rollback you won't 
get the data back

http://weblogs.sqlteam.com/mladenp/archive/2007/10/03/SQL-
Server-Why-is-TRUNCATE-TABLE-a-DDL-and-not.aspx

Truncate:

 - deallocates the data pages in a table and only this 
deallocation is stored in transaction log

 - aquires only table and page locks for the whole table. 
since no row locks are used less memory is required  (lock 
is a pure memory object)

 - resets identity column if there is one

 - removes ALL pages. NO empty pages are left behind in a 
table

 - fast(er)

 - doesn't fire delete triggers

Delete:

 - removes one row at the time and every deleted row is 
stored in the transaction log

 - aquires table and/or page and row locks for the whole 
table 

 - leaves identity column alone

 - can leave empty pages in a table since empty page 
removal requires a table lock which doesn't necessarily 
happen

 - slow(er)

 - fires delete triggers 


http://weblogs.sqlteam.com/mladenp/archive/2007/10/03/SQL-
Server-Why-is-TRUNCATE-TABLE-a-DDL-and-not.aspx

truncate provide faster processing than delete because of 
truncate does'n require transaction log uddation

Delete command removes the rows from a table based on the
condition that we provide with a WHERE clause. Truncate will
actually remove all the rows from a table and there will be
no data in the table after we run the truncate command.