why export file size of using conventional path export bigger than direct path export?

Hi there,

I am using export utility to export database

- mode 1: conventional path export (direct=no), output file size is 373M

- mode 2: direct path export (direct=yes), output filesize is 363M

number rows exported of two modes are the same

pls, tell me why filesize of using conventional path is bigger (10M) than direct path export

thanks,

Tieu Lan