Sessions more than processes ?

I cannot understand why the counts of V$SESSION large than the counts of V$PROCESS, even large to 2 ~ 3 times. but I don't have MTS configuration. In my mide, I suppose sessions are little than processes. am I wrong? Our clients are Oracle develop 2000.
Thanks for any help.

Check in your V$session for users marked as 'KILLED'.
If you have MTS configuration , sessions > processes.