What is the difference between SPfile and Pfile in oracle database?

Both SPFILE and PFILE are Oracle server initialization parameter files.

When an oracle server instance starts it reads the initialization parameters.

The contents of the parameter files includes but not limited to :

• The name of the database instance
• list of instance parameters
• The name and location of control files
• SGA Memory allocations
• Log archive and database recovery file location information

The difference between SPFILE and PFILE is:

• PFILE is a text file that can be modified manually but SPFILE is a binary file and can not modified manually.
•  When oracle database is installed SPFILE is the default parameter file and then we create PFILE from SPFILE.
• PFILE is  a backup of SPFILE.
• on SPFILE file parameter values changes  is made using ALTER SYSTEM command or by  creating SPFILE from PFILE after making changes on PFILE.

Note:  We can create SPFILE from PFILE and Vice versa.