Real Conditionals, Unreal Conditionals.

Real Conditionals:

• The verb in the if clause is in the present, even if it has future meaning.

                e.g: If you go tomorrow, call me.

• Can also be formed with the present continuous in the if clause.  

               e.g: If you are going tomorrow, call me

Unreal Conditionals: 

• When an unreal conditional if clause contains the verb be, use were for all subjects. 

               e.g: If I were on time, I'd walk to work.

• Unreal conditionals can also be formed with the past continuous in the if clause.

              e.g: If I were leaving now, I might walk to work. 

Link: http://www.myenglishpages.com/site_php_files/grammar-lesson-conditionals.php