w3c validator installed locally

hi,
i have installed the w3c validator locally on winxp using apache following
the steps here in the document
http://validator.w3.org/docs/install_win.html

but i am facing a problem. if i check some site with
http://validator.w3.org
it give me very little error

but when i check the same site with my local validator, it gives me a huge
list of errors.
why is this? same code running locally validates a site differently!!!

any help?

thank
Faraz