Difference between storing files on folder and in mysql db

Hey,

I would like to know what the differences are in terms of security,
reliability and resources between storing user-uploaded images in a
file or storing them in a mySQL database.

Our company is starting an image-competition soon, and I am not sure
if I should write the php script to insert the binary code into a
mySQL database or if I should just store the files in a dedicated
folder and the data about them in the mySQL database.

We are expecting relatively big loads of files, at least 10,000 in the
first 2 months.

Which system should I use? Is there a real difference between the two?
our server is apache2, if that has any effects on the answer..

Thank you!

Moriel Schottlender
.