Any difference between the back ups made by Titanium and Nandroid? I have both CWM and Titanium backup pro installed and will like to make a backup of my system (Xperia Neo V). However I'm torn between the two. I have about 3.6gb space left on my 14gb SD card and have move lots of apps to the card. Which option is best for me? Thanks in advance.
The two are actually quite different. Titanium backs up apps and settings only. Nandroid backs up everything including the OS. Titanium is useful when messing with apps and settings, since you have the option of restoring only what you want. Nandroid backups are largely for when you totally b0rk your phone and need to restore it to a more or less pristine state.

The biggest difference is that Titanium requires a working Android installation, while Nandroid only requires a working CWM or other custom recovery.

Just to clarify, Nandroid only backs up your /system, /data and a few other partitions. It does not backup your SD card. Titanium backup may back up some of the stuff on your SD card, but not necessarily all of it, only data that associated with an app will be backed up (and perhaps a few other things like photos and music).