What is the difference between PRE-FORM and WHEN-NEW-FORM-INSTANCE trigger?

• Pre-Form trigger will be fired before entering into the form. It is the first trigger that fires when a form is run; 

• Pre-Form fires before the form is visible. It is useful for setting access to form items, initializing global variables, and assigning unique primary key from an Oracle sequence.

• When-New-Form-Instance trigger will be fired whenever form is ready to accept the data from the user.

• Another main difference between the two is that you cannot navigate in a pre-from trigger (restricted) whereas you can navigate in a when-new-form-instance trigger. 

 For example : go_block and execute-query will only work in when-new-form-instance trigger not in pre-from trigger.