What options to use for diff?

["Alexander Farber (EED)" <eedalf@eed.ericsson.se>]

Hi,

I have read "man diff" and "man patch" and still 
have yet another stupid question: what command 
line options should I use when calling diff? 

I have tried following:

   diff -r mm-1.1.3-orig/ mm-1.1.3/ > xxx.diff

and:

   diff -r -c mm-1.1.3-orig/ mm-1.1.3/ > xxx.diff

and:

   maas24: diff -r -u mm-1.1.3-orig/ mm-1.1.3/ > xxx.patch
   diff: illegal option -- u
   usage: diff [-bitw] [-c | -e | -f | -h | -n] file1 file2
          diff [-bitw] [-C number] file1 file2
          diff [-bitw] [-D string] file1 file2
         diff [-bitw] [-c | -e | -f | -h | -n] [-l] [-r] [-s] [-S name] directory1 directory2

   (that's Solaris diff, but we have GNU diff around too)

but the resulting format looks different from
for example

http://www.openbsd.org/cgi-bin/cvsweb/ports/databases/postgresql/patches/patch-pg_passwd.c


Also what is the differences between the 4 formats,
which the "man patch" is talking about and which of
them is prefered (for OpenBSD ports and in general)?

Thanks
Alex

PS: 1) I hope to submit few changes to the mm port,
       that's why I am asking here

    2) I am using Solaris at work, so if you know
       that there is a difference between OpenBSD
       and Solaris diff options, please tell me.