"write memory"
Stores the current configuration in Flash memory, along with the activation key value and timestamp for when the configuration was last modified.
"write terminal"
Display current configuration on the terminal.
These two commands have completely separate responsibilities.
Here is a link for write command options-
http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/pix_sw/v_63/cmdref/tz.htm#wp1027782
Hope that helps.
Regards,
Vibhor.