Galaxy Ace 3 LTE has Qualcomm cpu, Snapdragon S4 Plus and gpu Adreno 305 so is much better than normal Ace 3.
Nothing against Xperia M...
Better Designe and Build
Better Software Optimization N lag-free
Better the Camera : http://www.gsmarena.com/piccmp.php3?idType=1&idPhone1=5479&idPhone2=5497
Better Chipset, and more Powerful Hardware
Better Battery Runtime
Better the price
So, What remains?! Samsung doesn't have anything to prove in the mid-range category...
Bet it's got a better speaker than the note 3. Can see that just from the picture. .