change vs modify

[evan at pedsgo.UUCP]

We are working on our backup scripts, and have found that ff has -c and -m
options, where c=file changed date, and m=file modified date.  In my
dictionary, change and modify are synonyms.  What is the difference to ff
and, I suppose, to all of Unix?
-- 
WHO: Evan L. Marcus                         ||  "This is between me and the
WHAT: Concurrent Computer Corporation,      ||   vegetable!"
WHERE: Tinton Falls, NJ                     ||      
HOW: {topaz|hjuxa|vax135}!petsd!pedsgo!evan ||  WHY: What the f--k!