[Techtalk] Different usage betweed df and du

[Sue Stones]

I received a message saying that /home is full.  (I deleted some stuff 
so that I can get some work done.)

When I run "df" it tells me that I have used 9.4 of my 11GB on /home 
(before I deleted stuff it said I had used 11G)

When I run "du" it tells me that /home has used 1.1GB.

What it the likely cause of this difference?  How do I go about sorting 
it out?

Thanks to anyone who can help.

sue