Logical Standby Database and Physical Standby Database

What is difference between physical standby and logical standby Database?  

                                                         OR

How  physical standby and logical standby Database differs?

There can be two type of standby database.

                 1) Physical standby   2) Logical Standby

The Standby database is called “physical” if the physical structure of stand by exactly matches with stand by structure. Archived redo log transferred from primary database will be directly applied to the stand by database.

The Stand by database is called “logical”, the physical structure of both 
databases do not match and from the archived redo log we create SQL statements then these statements will be applied to stand by database.That is, Logical standby uses LogMiner techniques to transform the archived redo logs into native DML statements (insert, update, delete). This DML is transported and applied to the standby database.  Logical standby database permits you to add additional objects like tables, indexes, etc to the database.

The difference between physical and logical standby is the way in which changes from the primary database are applied. Both created as an exact image of the primary database. Both receive redo logs from the primary database. The difference is that a physical standby is mounted (but not open) and applies the received redo logs just as in the case of media failure recovery. A logical standby reconstructs SQL statements from the received redo logs and executes them and applies them when our A logical standby is (must be) opened.