Difference between Truncate and Delete

Truncate and Delete both are used to delete data from the table. Both these commands will only delete the data of the specified table; they cannot remove the whole table: data along with structure.
TRUNCATE and DELETE remove the data not the structure
Both commands remove rows from a table, but the table structure and its columns, constraints, indexes, and so on remain. To remove the table definition in addition to its data, use the DROP TABLE statement.

Conditional based deletion of data
Conditional based deletion of data means that not all rows are deleted. Let's suppose I have a table authors and from this table I want to delete the authors that are living in Australia. Let's examine what our options for doing this with each command.
TRUNCATE - In case of the TRUNCATE command we can't perform the conditional based deletion because there is no WHERE clause allowed with this command.
DELETE - THe DELETE command provides the functionality of conditional based deletion of data from the table using the WHERE clause.

Delete and Truncate both are logged operations:
On most of the articles I have read on the Internet, I have seen this written: "delete is a logged operation and truncate is not a logged operation", which means when we run the delete command it logs (records) the information about the deleted rows and when we run the truncate command it doesn't log any data. But this is not true; truncate is also a logged operation but in a different way. It uses fewer system and transaction log resources than delete. The TRUNCATE command uses minimum logging resources, which is why it is faster than delete. So both delete and truncate are logged operations, but they work differently as shown below.

DELETE is a logged operation on a per row basis.
The DELETE statement removes rows one at a time and records an entry in the transaction log for each deleted row. So, in case if you are deleting a huge number of records then it can cause your transaction log to grow. This means the deletion of a huge number of records will use more server resources as it logs each and every row that is deleted. That is why your transaction log will grow very rapidly. Since the delete statement records each deleted row it is also slow. Some people ask that if this is done for each row then why does not Microsoft modify the delete statement to not record each deleted row??? The answer is when you run your databases in full recovery mode, detailed logging is necessary for SQL Server to be able to recover your database to the most recent state.

TRUNCATE logs the deallocation of the data pages in which the data exists. TRUNCATE is faster than DELETE due to the way TRUNCATE "removes" rows from the table. It won't log the deletion of each row; instead it logs the deallocation of the data pages of the table. The TRUNCATE statement removes the data by deallocating the data pages used to store the table data and records only the page deallocation in the transaction log. Actually, TRUNCATE does not remove data, but rather deallocates whole data pages and removes pointers to indexes. The data still exists until it is overwritten or the database is shrunk. This action does not require a lot of resources and is therefore very fast. It is a common mistake to think that TRUNCATE is not logged. This is wrong. The deallocation of the data pages is recorded in the log file. Therefore, "Books Online (BOL)" refers to TRUNCATE operations as "minimally logged" operations. You can use TRUNCATE within a transaction, and when this transaction is rolled-back, the data pages are reallocated again and the database is again in its original, consistent state.

Behavior of Delete and Truncate for identity columns
now the case of identity columns. Both the TRUNCATE and DELETE commands behave differently against Identity columns. When we use truncate it will reset the counter used by an identity column for new rows to the seed value defined for the column. But in the case of DELETE it will not reset the counter of your identity column. Rather it maintains the same counter for new rows. In both the cases, if no seed was defined the default value 1 is used. As TRUNCATE resets the identity column counter, in the case where you want to retain the identity counter, use DELETE instead of TRUNCATE.