Conventional path means that a SQL INSERT statement is used to load data into tables. Direct path deals with data much faster than conventional path. Direct path achieves this performance gain by inserting data directly, bypassing the SQL command processing layer and saves on data copies whenever possible.
This means you don't get any redo created however and once your load is complete you should backup immediately in order to have your data safe.
Lets elaborate them!
--Conventional path Export.
Conventional path Export uses the SQL SELECT statement to extract data from tables. Data is read from disk into the buffer cache, and rows are transferred to the evaluating buffer. The data, after passing expression evaluation, is transferred to the Export client, which then writes the data into the export file.
--Direct path Export.
When using a Direct path Export, the data is read from disk directly into the export session's program global area (PGA): the rows are transferred directly to the Export session's private buffer. This also means that the SQL command-processing layer (evaluation buffer) can be bypassed, because the data is already in the format that Export expects. As a result, unnecessary data conversion is avoided. The data is transferred to the Export client, which then writes the data into the export file.